Double hyphen in url gives 404 error, why?

Question

WordPress

The essence of the problem is that there are double hyphens in the url (site/nazvanie--tyt-tak), a 404 error is generated during the transition, if I save it like this (site/nazvanie-tyt-tak), then the page opens normally. Why is this happening?

Answer 1

I think that the problem is in the plugin that builds permalinks.
I recommend using Cyr to Lat enhanced