How do use/import/declare pages correctly

Hello there,
Maybe someone of you could enlighten me:

I dont understand, how i use a page, i created with ionic generate page examplepage, correctly.
Until know, i imported the page on the top of app.module.ts and added the name into declarations and entryComponents.

Everything worked fine, until i tried to run a --prod build.
There i get the error message that type Examplepage in examplepage.ts is part of the declarations of 2 modules:
app.module.ts and examplepage.module.ts

Could anyone please explain, what i am doing wrong and how can i fix this?

Thank you very much

Best regards
skee

See this post.