I deleted all songs from my iPhone, but iTunes claims I have two copies of the same song on the phone. They show up greyed out with a sync icon next to them. Syncing has no effect, and they can't be played or deleted from within iTunes.
On the iPhone itself, it sees no music. (Usage displays "No Data" next to music).
iTunes 10.7 and iOS 6.1 on iPhone 5. This has been an issue since I got the song in question via a "Song of the week" promotion on iTunes. (This song, and this song only, has been an issue.)