Album info "Album (artist)" not "Album"

Hey,

I've got a annoying problem. I have started to clean up and organize
my MP3's. Have you ever came over a MP3 file with no info at all, or
even worse, the wrong or totally useless info???

No, to my question. I'm using WMP9 swedish (maybe not every
translation is correct for the english version...). Going into the
"media libary" and clicking "All music" gets a list of all files in
the library. I'm always sorting after the filename column because I
have all artist in a correct named folder. Ok, starting to organize. I
use multiple marked files, then choose "edit" by right-clicking.
Entering the correct artist name and album name for the files in the
folder. Going back to list all artists. The name seems correct, but
clicking the +-sign does not show all files belonging to that album
(some are missing), hmm. Going back to "All music", the album
information seems correct, hmm again. Going into "List Albums", I see
that there are multiple entries of the same album in the following
manner.
"Album"
"Album (artist1)"
"Album (artist2)"
(every entry is belonging to the same album/folder)

Why?, trying to rename the album "Album (artist1)" to "Album" only
"Album" is showing so I can't rename it. For the files in question,
the column "Media info" in "All music" states "missing" (not "unknown"
or "found").