Confusion with the pages of the site https://rko-bank-24.ru and another site in Google?

Question

Google

There are two sites that are located on the same CMS Bitrix.
The essence of the problem:
in the webmaster's office I get 404s, which are formed by substituting the addresses of the pages of one site to another.
Example: 404 that pops up on the site http://bankcreditcards.ru, page /internet-mobilniy-bank/
It really does not exist and has never been within this site. But it is available on the site https://rko-bank-24.ru
We checked the sitemaps and site structure with several programs. There are no links to the page you are looking for. And never happened before.
Dear experts, please help me understand where the robot takes such pages from and how to overcome it?
ps Asked a question on the Google forum, but never received an answer.