Your right, it was. I cannot speak to the processes at tvdb but something within the last week or two resulted in it changing from 350665 → 465258 causing plex to now have two ids. You can see this very easily if you try and match using tvdb-350665 and tvdb-465258 as both match the show.
Whatever metadata code plex use to detect id changes appears to never or very rarely do cleanup when this type of thing happens (Dope Girls has been a problem since January). If your interested this script Audit duplicate Plex guids · GitHub from @SwiftPanda16 and this thread can provide more information.
