Oh, you're referring to the Display Unidentified FCC Licenses for XXXXX County XXXXXX link that takes you to a page titled FCC Assignments Not Identified for County?
If yes, that is an automatically generated list that shows FCC licenses that are not on the main county page. It's simply a list of licenses within the county that have not been assigned to any entries on the county page.
So in other words, XYZ Fire Dept licensed 46.320 under the ABC123 license decades ago, but stopped using that channel 15 years ago when they switched to VHF. Since there would be no listing for 46.320 on the county page, due to it no longer being valid, the ABC123 license is not assigned to any database entry. Therefore it shows up in the list of active FCC licenses that are not "identified" on the county page.
Note that active FCC license does not equal "actively used frequency". In fact many public safety licenses are automatically renewed even if the frequencies were abandoned long ago.