diff --git a/header.go b/header.go
index d32ea2c..468f30f 100644
--- a/header.go
+++ b/header.go
@@ -23,7 +23,7 @@ import (
 
 const (
 	// Version is semantic version.
-	Version = "0.2.18"
+	Version = "0.3.0"
 
 	// TokenTypeJwt is the JWT token type supported JWT tokens
 	// encoded and decoded by this library
diff --git a/imports.go b/imports.go
index b41f700..8a0f0c9 100644
--- a/imports.go
+++ b/imports.go
@@ -120,7 +120,14 @@ type Imports []*Import
 
 // Validate checks if an import is valid for the wrapping account
 func (i *Imports) Validate(acctPubKey string, vr *ValidationResults) {
+	toSet := make(map[Subject]bool, len(*i))
 	for _, v := range *i {
+		if v.Type == Service {
+			if _, ok := toSet[v.To]; ok {
+				vr.AddError("Duplicate To subjects for %q", v.To)
+			}
+			toSet[v.To] = true
+		}
 		v.Validate(acctPubKey, vr)
 	}
 }
diff --git a/imports_test.go b/imports_test.go
index 8a9bd3a..a08bcb0 100644
--- a/imports_test.go
+++ b/imports_test.go
@@ -348,3 +348,32 @@ func TestImportSubjectValidation(t *testing.T) {
 		t.Errorf("imports with valid contains subject should be valid")
 	}
 }
+
+func TestImportServiceDoubleToSubjectsValidation(t *testing.T) {
+	akp := createAccountNKey(t)
+	akp2 := createAccountNKey(t)
+	apk := publicKey(akp, t)
+	apk2 := publicKey(akp2, t)
+
+	account := NewAccountClaims(apk)
+
+	i := &Import{Subject: "one.two", Account: apk2, To: "foo.bar", Type: Service}
+	account.Imports.Add(i)
+
+	vr := CreateValidationResults()
+	account.Validate(vr)
+
+	if vr.IsBlocking(true) {
+		t.Fatalf("Expected no blocking validation errors")
+	}
+
+	i2 := &Import{Subject: "two.three", Account: apk2, To: "foo.bar", Type: Service}
+	account.Imports.Add(i2)
+
+	vr = CreateValidationResults()
+	account.Validate(vr)
+
+	if !vr.IsBlocking(true) {
+		t.Fatalf("Expected multiple import 'to' subjects to produce an error")
+	}
+}