This happens in layouts like "Playlist, Library & Context": when double-clicking a song in SongList with the option activate=addplay, it is added to playlist twice. It's been like this for at least several weeks now, presumably since this update, though I'm not sure. Admittedly it's not that much of a problem since alternatives (enter, spacebar, drag-and-drop, etc) work normally.

thanks for reporting it, I fixed it.