What Does It Mean?
The URLs contain hreflang tags that use the same URL for multiple hreflang languages.
Hreflang is a way to tell search engines that there are multiple versions of a page in different languages. This will help search engines serve visitors the most appropriate version of each URL by language or region.
Here's an example of hreflang tags for https://example.com/en-us/products, which is an English page targeting visitors in the United States that also has an English version targeting United Kingdom, a French version, a German version, and a default version available:
<link rel="alternate" hreflang="en-us" href="https://example.com/en-us/products" />
<link rel="alternate" hreflang="en-gb" href="https://example.com/en-gb/products" />
<link rel="alternate" hreflang="fr" href="https://example.com/fr/products" />
<link rel="alternate" hreflang="de" href="https://example.com/de/products" />
<link rel="alternate" hreflang="x-default" href="https://example.com/products" />
In this example, you'll notice that there are no URLs that appear for more than one hreflang. This should make sense, since you wouldn't want a single URL representing multiple languages. Each URL should only be used for exactly one hreflang language. If the same URL is used for more than one, it will be flagged as an issue.
Why It's Important
If hreflang tags are set incorrectly, search engines may ignore the tag completely. If this happens, it's possible search engines will get confused and the wrong version of the page could be ranked in a particular region or language.
For example, visitors from the UK could be served links to the US version of the page on search engines, or visitors from France could be served links to the Switzerland version.
How To Fix
Look at each URL of your site and see all of the hreflang tags on the page. Identify any URLs that appear more than once. For each of these, consider replacing all but one of them with an appropriate other URL or consider removing them completely.