I have quite a long playlist, and sometimes I’m listening to music and think to add the song I’m listening to to the playlist.
I feel that sometimes I am probably adding something that’s already on there, but I can’t tell because the playlist is so long. I’m looking for a feature where either I can click “find duplicates” and it will show me, or otherwise that will allow me to order the playlist by title so I can easily see duplicates myself.
Ideally it either wouldn’t let you add duplicates in the first place, or give you a warning when you are trying to do so, but at the very least a way to find and remove them would be great.
Thanks
You cannot add duplicates anyway.
It’s good to know I can’t unwittingly add the same track twice, thanks 
I assume this doesn’t apply if I have the same track on multiple albums and try to add a “different” track that is actually the same though?
That depends wholly on Musicbrainz.
If the album on there is using a different “recording”, then Plex is considering the two instances as different.
If the two albums use the same recording, then Plex will treat them as being one and the same. They will even share their star-rating.
Ah yeah I had noticed that. When they are recognized as the same they are both added to the playlist when you add one in the first place as far as I can tell. It would be much easier to tell (and remove) though if we were able to, for example, arrange my alphabetical order.
I’m glad to hear that I can’t literally accidentally add something again, but I’d still like to see something like that implemented.