the way categories are implemented is somewhat misleading.
If You are allowed to define different categories, the names within these categories should be independent. I.e. You should be allowed to enter two different media under the name "MyDisk27" in two different categories. As things are, the input of the second medium will overwritethe first one with the same name but different category.
If You have larger amounts of media, the retrieval is simplest via a numbering system. Surely You can use workaraounds ( CD0001, CD0002 , ... and Paintings0001, Paintings0002, ...) but this is somewhat awkward.