When I have a spec that defines the same thing twice (but in different namespaces) I get invalid code generated. For example, with a spec containing something like this (notice the reuse of the same identifier myThing for both the request body and the schema):

paths:
  /my/end/point:
    put:
      requestBody:
        $ref: '#/components/requestBodies/myThing'
components:
  requestBodies:
    myThing:
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/myThing'
      required: true
  schema:
    myThing:
      type: object
      properties:
        thing:
          type: string

Then I used up with a typedef in the generated code like: type MyThing MyThing which is invalid.

I've currently worked around this by altering typedef.tmpl to do the following:

{{range .Types}}
{{if ne .TypeName .Schema.TypeDecl }}
{{ with .Schema.Description }}{{ . }}{{ else }}// {{.TypeName}} defines model for {{.JsonName}}.{{ end }}
type {{.TypeName}} {{if and (opts.AliasTypes) (.CanAlias)}}={{end}} {{.Schema.TypeDecl}}
{{end}}
{{end}}

Which skips doing a typedef with a type name equal to it's schema declaration, but that is a bit of a hack and ideally the generator would create either unique names or be able to deduplicate identical types internally before iterating over them in the templates.