Yandex has updated their documentation around duplicate pages, including the wording around how they are defined.
Previously Yandex worded duplicate pages as being:
Pages are considered duplicates if they are available at different addresses, but have the same content. In this case, the indexing robot combines them into a group of duplicates. The search results will include only one of these pages-which will be selected by the robot.
This has been updated to:
If the site pages are available at different addresses, but have the same content, the Yandex robot can count them as duplicates and combine them into a group of duplicates.
Duplicate pages (and content) isn’t a new problem to Yandex Webmasters, and Yandex’s advice on dealing with duplicate pages is to use a canonical, or a 301 redirect if the page has no user value:
To get rid of duplicates and the consequences of their appearance, we recommend setting up the rel = “canonical” attribute for them, indicating the main address, or using a 301 redirect to the necessary pages – this will tell the robot which page should be in the search.
Yandex Duplicate Page FAQ
Q. The pages have almost the same address, will the robot consider them duplicates?
A. No, the content of the pages themselves is compared directly and the address does not matter.
Q. I have different photos on the pages, but the text is the same, will there be duplicates?
A. Yes, such pages will be deemed duplicate. For pages to be indexed separately from each other, differences in text content are required.
Q. There is nothing more to add to the product pages: they, for example, differ only in the photo, but the price and description are the same.
A. It might be worth reconsidering the structure of the site: such pages, it seems, will not be able to be found by relevant queries, so it is often worth combining them into one page and using it as a landing page for a group of queries.