Director appears twice on Plex's database

When classifying movies Plex is incorrectly making a double entry for director Michael Haneke. Get most of his movies under one “Michael Haneke” entry and then a separate entry for a second “Michael Haneke” for his movie “Happy ending”. How can I merge both Michael Haneke’s?

Have a look here Plex is creating new/duplicate Tags for Directors and Actors that are already in my server - #6 by drzoidberg33

Full metadata refresh of your libraries with optimise db afterwards should resolve the problem.