probably a bug. bliss combines different artists with the same album name
So clearly the album name is a primary key but there are many instances where the same album name is used by different artists and Bliss does not appear to handle these. "Greatest Hits" is a great example. Maybe make album artist a secondary key and adjust the logic to suit?
The album artist _and_ the album name is a _sort_ of primary key.
I think this might happen if the files are in the same folder. Is that the case for you?