This matters because specific publications are sometimes edited, making them slightly unique. Although I can download a copy of something by Jane Austen from one of the archive sites on the web, I can't legally scan and upload a particular printed version. Similarly if I translate something by Plato into English, the translation remains in copyright, even though the original Greek is in the public domain.

I can't see how it's possible to prevent a performance of the music on an old manuscript, unless the manuscript was stolen. The owners own the manuscript. If the music on it is already public, it remains public. If it wasn't public and was copied without permission, they have a case of sorts based on the loss of value of their original, but it's not quite a standard copyright case.