The 1996 episode titled "The One with the Jam" saw David Arquette’s character "Malcolm" stalking "Phoebe" (Lisa Kudrow) because he mistook her for her twin sister "Ursula". Although she corrected him early on, "Phoebe" ends up justifying "Malcolm’s" behavior and falling for him, and invites "Malcolm" to stalk her instead of "Ursula". The creators revealed it was hard for Kudrow to play in episodes with a double.
A second episode that Kauffman would rather never existed
Kauffman also added that she "wasn’t sure that chickenpox worked either," referring to an episode in which "Phoebe" gave the illness to a Navy sailor (Charlie Sheen) whom she dated when he was in town. She revealed that these episodes took a lot of time to film and a lot of rewriting to make the episodes work.