Option to disallow duplicate files in playlists

[antgel]

This is not a bug, rather a feature request. I classically listen to albums, but more recently I have started using playlists for various situations. I note that if I add a song to a playlist, and the song is already there, it gets added again. It would be a great way to prevent duplicates. I guess sometimes this is a feature, so it should be an option.

My personal use case: I have far too many albums to go through them in an orderly fashion and add songs to a specific playlist. But sometimes something catches my eye in the random view and I want to add it to a playlist, but I don't know if it's already there (the playlist is long as well).