How do search engines treat duplicate content on a page?

Question

css

Hello. There is a page, it is adaptive, but the method of presenting information is different on the PC and mobile versions (for example, on the PC, anchor links are used to access information, and on the mobile version it all adds up to hiding / drop-down lists - joxi.ru/vAWljLqT1wyYEr) , so it was decided to do this: on the PC version, a separate block is used for this, which is hidden on the mobile version (display: none;), and on the mobile version, the mobile block is already shown.
But, as I was told, search engines treat this very badly, because. duplicate content on the page. How bad is that for search engines? How can this be avoided, is it worth considering creating a separate mobile version of the page using a different url?

Answer 1

as an option, check if the mobile version, then output the block and vice versa. That is, it’s not just to hide it through css, but not to display it completely.
Just not through JS. as far as I remember, robots don't care about js, they sometimes go without it.