A URL with a slash is different from a URL without a slash.
A URL with a slash indicates a folder (for e.g https://ahrefs.com/blog/). A URL without a slash indicates a file (for e.g https://ahrefs.com/blog).
Since URL Rating (UR) is the rating of a particular page, they will have different URs as they are considered different pages.
Note: You can also see this difference for http/https URLs as well as www/non-www URLs.