All in the Family
The character of Serena, Samantha’s identical cousin, was mostly created as a foil to Serena, showing off the differences between two identical yet opposite witches. The juxtaposition led to some funny incidents, especially when Serena would act as a stand-in for Samantha. However, the two characters do share similarities–besides for being played by the same actress, of course.
For instance, Serena’s character also has a thing for mortals. While Samantha went and married one, Serena is keener on dating them and being around them in general. While it would be interesting to see them interact, the two characters were rarely in the same scene, as the technology to do so was not so available at the time. However, there are a few scenes where Samantha and Serena interact, thanks to TV magic and a body double.