If you have self-made compilation albums in iTunes that appear as multiple albums with the same name on your iPhone / iPod, try wiping the “album artist” field even if it appears empty. Select all songs, get info, check the album artist box & OK.
With the id3v2 commandline tool (available via fink in MacOS), it should be as simple as:
id3v2 --TPE2 "" *.mp3
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