How to make for duplicate pages not a 301 redirect, but specify the 404 code?

Question

htaccess

Hi all!
On the site, the Wordpress engine has duplicate pages with the indicated problems (below), a 301 redirect was implemented on them, while in htaccess the set is "standard for Wordpress" and who sends the 301 redirect is not clear, revised wherever possible.
Since a multiple 301 redirect harms the site, tell me who knows how to set not 301 but code 404 on such pages. I
compared competitor sites to such pages on such pages it costs 404.
I tried to find a solution on the Internet myself, but it doesn’t work. Help!
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1. Adding arbitrary characters to the end of the URL, forming a new nesting.
Example: https://apteka.ru/moskva/apteki/doktor-stoletov_16/
and
https://apteka.ru/moskva/apteki/doktor-stoletov_16/Lfz/ . _
2. Adding nesting with arbitrary characters. For example
, https://www.utkonos.ru/news/item/1343
and
https://www.utkonos.ru/news/wg/item/1343 . Thanks for the help!