diff --git a/packages/govuk-frontend/src/govuk/components/accordion/accordion.puppeteer.test.js b/packages/govuk-frontend/src/govuk/components/accordion/accordion.puppeteer.test.js
index 0dff09e761..82f575cf56 100644
--- a/packages/govuk-frontend/src/govuk/components/accordion/accordion.puppeteer.test.js
+++ b/packages/govuk-frontend/src/govuk/components/accordion/accordion.puppeteer.test.js
@@ -1,3 +1,5 @@
+/* eslint-disable no-new */
+
 const {
   goToExample,
   render,
@@ -712,6 +714,21 @@ describe('/components/accordion', () => {
           })
         })
 
+        it('throws when initialised twice', async () => {
+          await expect(
+            render(page, 'accordion', examples.default, {
+              async afterInitialisation($module) {
+                const { Accordion } = await import('govuk-frontend')
+                new Accordion($module)
+              }
+            })
+          ).rejects.toMatchObject({
+            name: 'InitError',
+            message:
+              'Root element (`$module`) already initialised (`govuk-accordion`)'
+          })
+        })
+
         it('throws when $module is not set', async () => {
           await expect(
             render(page, 'accordion', examples.default, {
diff --git a/packages/govuk-frontend/src/govuk/components/button/button.puppeteer.test.js b/packages/govuk-frontend/src/govuk/components/button/button.puppeteer.test.js
index e6b3bf6590..dda57595a9 100644
--- a/packages/govuk-frontend/src/govuk/components/button/button.puppeteer.test.js
+++ b/packages/govuk-frontend/src/govuk/components/button/button.puppeteer.test.js
@@ -1,3 +1,5 @@
+/* eslint-disable no-new */
+
 const { render } = require('@govuk-frontend/helpers/puppeteer')
 const { getExamples } = require('@govuk-frontend/lib/components')
 
@@ -329,6 +331,21 @@ describe('/components/button', () => {
         })
       })
 
+      it('throws when initialised twice', async () => {
+        await expect(
+          render(page, 'button', examples.default, {
+            async afterInitialisation($module) {
+              const { Button } = await import('govuk-frontend')
+              new Button($module)
+            }
+          })
+        ).rejects.toMatchObject({
+          name: 'InitError',
+          message:
+            'Root element (`$module`) already initialised (`govuk-button`)'
+        })
+      })
+
       it('throws when $module is not set', async () => {
         await expect(
           render(page, 'button', examples.default, {
diff --git a/packages/govuk-frontend/src/govuk/components/character-count/character-count.puppeteer.test.js b/packages/govuk-frontend/src/govuk/components/character-count/character-count.puppeteer.test.js
index 9cf41b60b3..a7cb85164c 100644
--- a/packages/govuk-frontend/src/govuk/components/character-count/character-count.puppeteer.test.js
+++ b/packages/govuk-frontend/src/govuk/components/character-count/character-count.puppeteer.test.js
@@ -1,3 +1,5 @@
+/* eslint-disable no-new */
+
 const { setTimeout } = require('timers/promises')
 
 const { render } = require('@govuk-frontend/helpers/puppeteer')
@@ -814,6 +816,21 @@ describe('Character count', () => {
         })
       })
 
+      it('throws when initialised twice', async () => {
+        await expect(
+          render(page, 'character-count', examples.default, {
+            async afterInitialisation($module) {
+              const { CharacterCount } = await import('govuk-frontend')
+              new CharacterCount($module)
+            }
+          })
+        ).rejects.toMatchObject({
+          name: 'InitError',
+          message:
+            'Root element (`$module`) already initialised (`govuk-character-count`)'
+        })
+      })
+
       it('throws when $module is not set', async () => {
         await expect(
           render(page, 'character-count', examples.default, {
diff --git a/packages/govuk-frontend/src/govuk/components/checkboxes/checkboxes.puppeteer.test.js b/packages/govuk-frontend/src/govuk/components/checkboxes/checkboxes.puppeteer.test.js
index 1d046fc725..a87cb2fe05 100644
--- a/packages/govuk-frontend/src/govuk/components/checkboxes/checkboxes.puppeteer.test.js
+++ b/packages/govuk-frontend/src/govuk/components/checkboxes/checkboxes.puppeteer.test.js
@@ -1,3 +1,5 @@
+/* eslint-disable no-new */
+
 const {
   goToExample,
   getAttribute,
@@ -363,6 +365,21 @@ describe('Checkboxes', () => {
           })
         })
 
+        it('throws when initialised twice', async () => {
+          await expect(
+            render(page, 'checkboxes', examples.default, {
+              async afterInitialisation($module) {
+                const { Checkboxes } = await import('govuk-frontend')
+                new Checkboxes($module)
+              }
+            })
+          ).rejects.toMatchObject({
+            name: 'InitError',
+            message:
+              'Root element (`$module`) already initialised (`govuk-checkboxes`)'
+          })
+        })
+
         it('throws when $module is not set', async () => {
           await expect(
             render(page, 'checkboxes', examples.default, {
diff --git a/packages/govuk-frontend/src/govuk/components/error-summary/error-summary.puppeteer.test.js b/packages/govuk-frontend/src/govuk/components/error-summary/error-summary.puppeteer.test.js
index c3788e8e86..285a0ecd17 100644
--- a/packages/govuk-frontend/src/govuk/components/error-summary/error-summary.puppeteer.test.js
+++ b/packages/govuk-frontend/src/govuk/components/error-summary/error-summary.puppeteer.test.js
@@ -1,3 +1,5 @@
+/* eslint-disable no-new */
+
 const { goToExample, render } = require('@govuk-frontend/helpers/puppeteer')
 const { getExamples } = require('@govuk-frontend/lib/components')
 
@@ -236,6 +238,21 @@ describe('Error Summary', () => {
       })
     })
 
+    it('throws when initialised twice', async () => {
+      await expect(
+        render(page, 'error-summary', examples.default, {
+          async afterInitialisation($module) {
+            const { ErrorSummary } = await import('govuk-frontend')
+            new ErrorSummary($module)
+          }
+        })
+      ).rejects.toMatchObject({
+        name: 'InitError',
+        message:
+          'Root element (`$module`) already initialised (`govuk-error-summary`)'
+      })
+    })
+
     it('throws when $module is not set', async () => {
       await expect(
         render(page, 'error-summary', examples.default, {
diff --git a/packages/govuk-frontend/src/govuk/components/exit-this-page/exit-this-page.puppeteer.test.js b/packages/govuk-frontend/src/govuk/components/exit-this-page/exit-this-page.puppeteer.test.js
index cdd37cf7c8..452b206428 100644
--- a/packages/govuk-frontend/src/govuk/components/exit-this-page/exit-this-page.puppeteer.test.js
+++ b/packages/govuk-frontend/src/govuk/components/exit-this-page/exit-this-page.puppeteer.test.js
@@ -1,3 +1,5 @@
+/* eslint-disable no-new */
+
 const { setTimeout } = require('timers/promises')
 
 const { goToExample, render } = require('@govuk-frontend/helpers/puppeteer')
@@ -231,6 +233,21 @@ describe('/components/exit-this-page', () => {
         })
       })
 
+      it('throws when initialised twice', async () => {
+        await expect(
+          render(page, 'exit-this-page', examples.default, {
+            async afterInitialisation($module) {
+              const { ExitThisPage } = await import('govuk-frontend')
+              new ExitThisPage($module)
+            }
+          })
+        ).rejects.toMatchObject({
+          name: 'InitError',
+          message:
+            'Root element (`$module`) already initialised (`govuk-exit-this-page`)'
+        })
+      })
+
       it('throws when $module is not set', async () => {
         await expect(
           render(page, 'exit-this-page', examples.default, {
diff --git a/packages/govuk-frontend/src/govuk/components/header/header.puppeteer.test.js b/packages/govuk-frontend/src/govuk/components/header/header.puppeteer.test.js
index d4f81f1f81..ec37001e69 100644
--- a/packages/govuk-frontend/src/govuk/components/header/header.puppeteer.test.js
+++ b/packages/govuk-frontend/src/govuk/components/header/header.puppeteer.test.js
@@ -1,3 +1,5 @@
+/* eslint-disable no-new */
+
 const { render } = require('@govuk-frontend/helpers/puppeteer')
 const { getExamples } = require('@govuk-frontend/lib/components')
 const { KnownDevices } = require('puppeteer')
@@ -179,6 +181,21 @@ describe('Header navigation', () => {
         })
       })
 
+      it('throws when initialised twice', async () => {
+        await expect(
+          render(page, 'header', examples.default, {
+            async afterInitialisation($module) {
+              const { Header } = await import('govuk-frontend')
+              new Header($module)
+            }
+          })
+        ).rejects.toMatchObject({
+          name: 'InitError',
+          message:
+            'Root element (`$module`) already initialised (`govuk-header`)'
+        })
+      })
+
       it('throws when $module is not set', async () => {
         await expect(
           render(page, 'header', examples.default, {
diff --git a/packages/govuk-frontend/src/govuk/components/notification-banner/notification-banner.puppeteer.test.js b/packages/govuk-frontend/src/govuk/components/notification-banner/notification-banner.puppeteer.test.js
index 0137d49c76..8b1c0a44cf 100644
--- a/packages/govuk-frontend/src/govuk/components/notification-banner/notification-banner.puppeteer.test.js
+++ b/packages/govuk-frontend/src/govuk/components/notification-banner/notification-banner.puppeteer.test.js
@@ -1,3 +1,5 @@
+/* eslint-disable no-new */
+
 const { render } = require('@govuk-frontend/helpers/puppeteer')
 const { getExamples } = require('@govuk-frontend/lib/components')
 
@@ -236,6 +238,21 @@ describe('Notification banner', () => {
       })
     })
 
+    it('throws when initialised twice', async () => {
+      await expect(
+        render(page, 'notification-banner', examples.default, {
+          async afterInitialisation($module) {
+            const { NotificationBanner } = await import('govuk-frontend')
+            new NotificationBanner($module)
+          }
+        })
+      ).rejects.toMatchObject({
+        name: 'InitError',
+        message:
+          'Root element (`$module`) already initialised (`govuk-notification-banner`)'
+      })
+    })
+
     it('throws when $module is not set', async () => {
       await expect(
         render(page, 'notification-banner', examples.default, {
diff --git a/packages/govuk-frontend/src/govuk/components/radios/radios.puppeteer.test.js b/packages/govuk-frontend/src/govuk/components/radios/radios.puppeteer.test.js
index 37561d3372..0eda543b15 100644
--- a/packages/govuk-frontend/src/govuk/components/radios/radios.puppeteer.test.js
+++ b/packages/govuk-frontend/src/govuk/components/radios/radios.puppeteer.test.js
@@ -1,3 +1,5 @@
+/* eslint-disable no-new */
+
 const {
   goToExample,
   getProperty,
@@ -316,6 +318,20 @@ describe('Radios', () => {
       })
     })
 
+    it('throws when initialised twice', async () => {
+      await expect(
+        render(page, 'radios', examples.default, {
+          async afterInitialisation($module) {
+            const { Radios } = await import('govuk-frontend')
+            new Radios($module)
+          }
+        })
+      ).rejects.toMatchObject({
+        name: 'InitError',
+        message: 'Root element (`$module`) already initialised (`govuk-radios`)'
+      })
+    })
+
     it('throws when $module is not set', async () => {
       await expect(
         render(page, 'radios', examples.default, {
diff --git a/packages/govuk-frontend/src/govuk/components/skip-link/skip-link.puppeteer.test.js b/packages/govuk-frontend/src/govuk/components/skip-link/skip-link.puppeteer.test.js
index cd3b7f8cc1..6b0f614f09 100644
--- a/packages/govuk-frontend/src/govuk/components/skip-link/skip-link.puppeteer.test.js
+++ b/packages/govuk-frontend/src/govuk/components/skip-link/skip-link.puppeteer.test.js
@@ -1,3 +1,5 @@
+/* eslint-disable no-new */
+
 const { render } = require('@govuk-frontend/helpers/puppeteer')
 const { getExamples } = require('@govuk-frontend/lib/components')
 
@@ -119,6 +121,21 @@ describe('Skip Link', () => {
       })
     })
 
+    it('throws when initialised twice', async () => {
+      await expect(
+        render(page, 'skip-link', examples.default, {
+          async afterInitialisation($module) {
+            const { SkipLink } = await import('govuk-frontend')
+            new SkipLink($module)
+          }
+        })
+      ).rejects.toMatchObject({
+        name: 'InitError',
+        message:
+          'Root element (`$module`) already initialised (`govuk-skip-link`)'
+      })
+    })
+
     it('throws when $module is not set', async () => {
       await expect(
         render(page, 'skip-link', examples.default, {
diff --git a/packages/govuk-frontend/src/govuk/components/tabs/tabs.puppeteer.test.js b/packages/govuk-frontend/src/govuk/components/tabs/tabs.puppeteer.test.js
index 99326cf177..aa6682edfa 100644
--- a/packages/govuk-frontend/src/govuk/components/tabs/tabs.puppeteer.test.js
+++ b/packages/govuk-frontend/src/govuk/components/tabs/tabs.puppeteer.test.js
@@ -1,3 +1,5 @@
+/* eslint-disable no-new */
+
 const { render } = require('@govuk-frontend/helpers/puppeteer')
 const { getExamples } = require('@govuk-frontend/lib/components')
 const { KnownDevices } = require('puppeteer')
@@ -269,6 +271,20 @@ describe('/components/tabs', () => {
         })
       })
 
+      it('throws when initialised twice', async () => {
+        await expect(
+          render(page, 'tabs', examples.default, {
+            async afterInitialisation($module) {
+              const { Tabs } = await import('govuk-frontend')
+              new Tabs($module)
+            }
+          })
+        ).rejects.toMatchObject({
+          name: 'InitError',
+          message: 'Root element (`$module`) already initialised (`govuk-tabs`)'
+        })
+      })
+
       it('throws when $module is not set', async () => {
         await expect(
           render(page, 'tabs', examples.default, {