Duplication of blocks in the layout of adaptive designs. Are there any downsides?

Question

HTML

What can be negatively affected by duplication of blocks in the site code created for adaptability?
For example, we show one block on laptops, another on phones and tablets.
Can this do any harm to SEO?

Answer 1

Well, if there is not text but menus, then search engines in general recognize them normally now and do not take them into account. In general, media in css and there are no problems with menu duplication ...

Answer 2

To be sure, put !-- noindex-- on one of the blocks.