How to make semantically HTML5 markup with non-unique content in the main tag?

Question

HTML

Greetings
They write that in HTML5 an element cannot contain non-unique content that is repeated on other pages, but what if the page in the center of the article should have a form or a short list of prices or something else that is repeated on other pages of the site?
Let me give you an example:
main
- unique material
- form (non-unique)
- unique material
- prices (non-unique)
To score on markup and do without it - is this the only option?

Answer 1

I didn’t quite understand the question, but if you want to check if your semantics are correct, then just take and paste all your html and paste it here . And everything will be clear!

Answer 2

Here is an example:
main
- unique material
- form (non-unique)
- unique material
- prices (non-unique)

In general, if we consider the main block as a whole - it is unique - this is the first time.
Two, where did you get such a rule about uniqueness from? There is no such thing in the specification, the specification does not consider your site as a whole at all, but each individual page individually.