My favorite episode of FH that featured both the Olsen Twins in a scene is part 1 of 'The Seven-Month Itch' from Season 1, when Jesse is having a nightmare in which he sees two Michelles in front of his eyes. I thought that was hysterical. (I think that was Dave Coulier doing their voices in that scene, since they couldn't talk yet.)

The other episodes to use both twins in the same scene are the Greek Wedding episode that kicked off Season 4 (where one of them wore a black wig), a Season 5 episode where Michelle gets grounded after playing with Jesse's equipment (there was a scene where "Good Michelle" and "Bad Michelle" are each trying to convince her whether or not to runaway), and of course, the last episode of FH where Michelle has amnesia and one of the twins plays Michelle's memory.

The best episodes that feature Mary-Kate & Ashley are the following:

1. "The Seven-Month Itch"
2. "Greek Week"
3. "The Devil Made Me Do It"
4. "Michelle Rides Again"

Gosh. They were all good. I guess I'm going to go with "Greek Week."

Yeah, I think Greek Week was the best. It was when they were just figuring out the whole acting thing, but were still unbelievably cute.

1. "The Seven-Month Itch"
2. "Greek Week"
3. "Michelle Rides Again"
4. "The Devil Made Me Do It"

The Seven-Month Itch was my favorite...I thought it was hilarious.