In my project I am using k2. Eventually noticed that the doubles are created: site.com/category/subcategory/item-name and site.com/item-name. Both links work! Maybe someone met this problem and have a solution?

Does the site.com/item-name refer to a menu, or did you use K2's advanced SEF?

I use artio joomser. the menu looks like this: main category/subcategory . Main menu indicates the main category and displays all content categories and subcategories.

The site.com/item-name and site.com/id-item-name pattern can only be accessed with three ways.

a) By enabling K2's advanced SEF from K2's params
b) By using an SEO extension (which you are using to the best of my knowledge)
c) By mapping the K2 item into a menu item.

If you have not done either a nor c then, you need to check the extension you are using for such a setting.

Finally if your extension handles properly canonical tags (eg: all these links point to the same URL), then you can safely disregard this issue.

The problem is still relevant. Google search 120 console shows duplicate meta descriptions. Duplicate links. site.com/item-name and site.com/category/category/item-name. Use only standard K2 SEF and Joomla SEF. What can you recommend Krikor?

Hello German and Happy New Year,

A K2 Canonical plugin will solve this issue.

Happy New Year, Krikor. And there are no other solutions? Simply this plugin will do the extra load and it paid?

I do not know if there free plugins which offer this functionality.
The rel=canonical tag passes the same amount of link juice (ranking power) as a 301 redirect, and often takes much less development time to implement. The tag is part of the HTML head of a web page.

I understand Krikor. However, it is not clear where such links takes google crawler, when on my website, but there is only references of the form site.com/category/category/item-name. Maybe you have any ideas?

I have experiencing the same issue, you can access pages with or without the parent category. I am using the K2 Advanced SEF feature.

This really needs to be fixed (without the use of a SEF extension)

In the meantime, there is a free canonical extension:
styleware.eu/store/item/26-styleware-content-canonical-plugin

Here is an article on the subject:
joomlaseo.com/seo-extensions/canonical

Note: I saw in the JED that the extension does not work when cache is enabled.

Here is a paid solution with good reviews:
extensions.joomla.org/extensions/extension/site-management/seo-a-metadata/canonical-links-all-in-one