What do I need to do to prevent the iOS 7 Music app from listing songs twice when the song should only exist once?
I sync a selection of playlists to my iPhone 5s from iTunes 11.1.5 on my iMac running OS X 10.7.5. For at least one artist, album tracks are listed twice on my iPhone despite appearing only once in my iTunes library. I count 16 duplicates out of 53 songs for this artist on my phone. (The artist is Front 242, which I mention mostly for my own reference.)
I checked my iTunes library on the iMac, and I only have one copy of the affected songs there.
I am not using iTunes Match.
Curiously, during playback, songs are not repeated if I move forwards or backwards through a list that includes duplicated songs.
What I tried
In an attempt to solve this, I unchecked "Sync Music" and applied the change with my iPhone connected to my iMac, so all songs were removed. Then I checked "Sync Music" again (and thankfully my previous selection of playlists was preserved), and the music went back on my phone. Same problem.
What I didn't try
I haven't tried marking either individual albums or the artist for inclusion on my phone, just one or more playlists that include these songs.
I haven't tried swiping to delete individual songs, because I'd first want to determine all of the playlists containing that song, and do a time-consuming before-and-after check on my phone to ensure that removing the apparently duplicated song doesn't change my playlists.