So, at least two CDs now have Plusα logos on an image in one place, and not Plusα in other places, the ones in question are:
SCDC-00050:
http://vgmdb.net/album/3808
SCDC-00106:
http://vgmdb.net/album/3831
I figured it'd be best to just see if anyone else wants to help research in the main forum what has it and what doesn't, or look around and see if we can figure out the story behind it.