For instance, in https://www.themoviedb.org/tv/64432-the-magicians/season/4/episode/7?language=en-US it was revealed that Mageina Tovah's https://www.themoviedb.org/person/20645-mageina-tovah?language=en-US character is named Zelda. If this and all subsequent appearances name her as Zelda it will look like two characters in her overview (in this case I guess it would be possible to use Zelda, The Librarian). At present it seems as if the only recourse is to go into each individual episode.
Similarly, someone added Jim Beaver as a regular to the cast of https://www.themoviedb.org/tv/1622-supernatural/season/14?language=en-US, which he definitely isn't. However the only way to add him to the relevant eps would be to open each one. (I may do this, as he's only been in a handful of eps).