Where do duplicate pages come from in upper case?

Question

Search Engine Optimization

Hello, I want to understand how duplicate pages are generated in the uppercase url site.ru/faq site.ru/FAQ And how best to hide them from indexing 301 redirect or canonical?

Answer 1

I'm setting up 301 for myself. Why canonical?

Answer 2

if available both ways, then canonical
here only guessing on the bones, many options

Answer 3

I want to understand how duplicate pages are generated in the url in uppercase

Crookedly configured bots walk around the site by url with characters in the upper register, visits are tracked by the Yandex.Metrica counter and get into the search results.