Reproducion steps

• Generate C# sources for both files Message1 and Message2:

1. quicktype --src Message1.json --src-lang schema --lang csharp --features attributes-only --namespace MyNamespace --out Message1.cs
2. quicktype --src Message2.json --src-lang schema --lang csharp --features attributes-only --namespace MyNamespace --out Message2.cs

• Expected: code should compile.

• Actual result: code won't compile because Message1 and Message2 define the same MyEnumType.