Which Witch is Which? is the 24th episode of the first season of the Bewitched
Endora poses as Samantha so she can take her place at a dress fitting. But an author, Bob Frazer, falls for Endora-Samantha, the worst part being that Gladys has seen them both together. Darrin tells the real Samantha that Bob Frazer is visiting them, and Bob mistakes her for the woman he met in the department store, which was Endora. Sam confronts Endora about it, and Endora, as Sam, tries to break it up with Bob. To break the confusion in this episode, Bob thinks that Endora-Sam and Samantha are identical twins.
- According to "The Bewitched Book" (Herbie J. Pilato, 1992), Liz Montgomery used the personality of her cousin "Panda" as part of the inspiration on how to play the "Endora/Samantha" double. Later, Liz would use her cousin Panda's persona as the basis for creating Samantha's cousin Serena.
- Gladys calls Samantha by her first name for the first time.
- Samantha has a fitting for a "new" dress that she wore in three previous episodes: episodes 7, 10 and 13
- This episode was filmed on January 18, 1965.