When the track properties has Disk!=0 lyrics texts are read from online sources normally, but locally are handled incorrectly. Instead of "path/track_file_name.txt" they are saved into "path/Disk#.txt" and read from there if this file is already present.
This means the same file 1.txt or 2.txt is used for lyrics of the whole album - obviously, usually isn't the right way to handle them.

You must have changed the default settings in the lyrics plugin, the default uses %a (for artist) and %t (for title), you must have added %d (for disc). I should maybe add a way to reset to the default, and a tooltip to dhow common variables. (you can also use long name variables with $ : $artist $title)

Ha, you're right: it was "./%d.txt" - for some reason gmusicbrowser does fallback when Disc==0, and when there's something else...
Moved config, the default turned out to be"~/.lyrics/%a/%t.lyric". I certainly won't keep it in ~/.anywhere/, but can't remember how i changed it and no idea why i'd come up specifically with %d without any instruction.
"./$track - $title.txt" fixes everything.
Thanks, sorryaboutthat.