Star Wars Rebels Season 2, Episode 22: "Twilight of the Apprentice
The Clone Wars Season 7, Episode 10: "The Phantom Apprentice
Just the two, there are. No more, no less. Okay, I may be missing any references in books, but as far as television series, these are it. Rebels takes place after TCW, but aired "first" and was portrayed as a rematch of sorts, albeit very briefly. TCW being the main one, presuming that is the episode you're wondering about.
