Why is this important?
This typically comes from developers adding version numbers or timestamps to page resources, and can be problematic as you lose the ability to cache the resources across multiple pages. In reality, if this only affects a handful of URLs this is not a big issue, but if it affects thousands of URLs then it is a much bigger problem.
What does the Hint check?
Examples that trigger this Hint:
CSS file URLs that are identical, save for the query string:
How do you resolve this issue?
This sort of issue is really only damaging if it is very widespread, so it is important to understand the scale of the problem. If the issue affects thousands of files, you will need to investigate the root cause of the problem. This issue typically occurs because developers add new version numbers to updated resource URLs, in order to force browsers to fetch the new URL rather than using a previously cached version. However, the pages/templates *should* be updated to only include the latest, up-to-date resource URL.
If these outdated URLs are still being referenced on lots of URLs on the site, you will need to work through the pages/templates/scripts to ensure that they are updated to the latest version, and perhaps consider running a script to help with version control.