Background: I relocated my music library to a different hard drive on my Mac. In order to sync iTunes, I exported the playlist, edited all the file paths to the new location, and imported it back into iTunes. It worked fine, except:
Now I have duplicate "most played", "most recently played", "classics" etc in the automatic playlists section in the left pane, both in iTunes and on my iPhone. (My Mac is localized to Swedish, so these playlist names are my own off the cuff translations back to English.)
I have looked at the XML playlist file I imported and could not find any entries there which would have caused the duplication, so starting over does not seem like a viable approach.
I have added album art, play times etc to the songs in iTunes so I would rather not start over from an empty music library. None of this is purchased via iTunes (and frankly I'd rather be without iTunes altogether); I have transferred my CDs to FLAC over the years and just converted them to MP4 for import into iTunes when I first got an iPod Touch a few years ago.