Bewitched

Which Witch Is Which? (1x24)

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DOUBLE DOPPELGANGER ALERT! 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.