This may not remove the duplicate from the plex back-end. Its been confirmed by their development team that they do not cleanup ids well and it requires manual intervention on their side. See thread Double plex guids validation for movies, series and episodes - #7 by drzoidberg33 if your interested were I pointed out I have almost 400 duplicates across movies, shows and episodes.
Anyhow, lets see, this might be the exception to the rule!
