Hi,
same happened to me. I used Cover Art LMCE feature some time ago and now I was cleaning my media library and spotted that I have several cover arts in moajority of files that I didn't select for sure....
I still don't like the UpdateMediaDaemon way of doing things. I'm not sure why it doesn't use one of more standard way of dealing with metadata (folder.jpg, maybe xml meta files, etc...) and therefore all these problems would be smaller....
Regards,
Bulek.