Try adding TMDB or TVDB tags in the show folder title. It would look like the following:
Fullmetal Alchemist (2003) {tmdb-37863} or {tvdb-75579}
Fullmetal Alchemist Brotherhood (2009) {tmdb-31911} or {tvdb-85249}
After you do that, try a Plex Dance and hopefully you shouldn’t have the problem anymore.
