Yeah, I feel the pain, I have live shows that get combined also. I changed my folder structure a little bit to help Plex figure it out.
I use this folder structure: Artist / AlbumArtist - AlbumTitle
I make the album title something different usually just add a date of the live show. Its spotty though.
So I make each live album a Disc 1 of 1 in the meta tag and it sometimes helps. Again spotty.
The other thing I have tried is simply unmatching the discs from plex then refreshing.
