This episode was written very cleverly and raises the biggest question of all for our heroes: if you slid into a world that was nearly identical to yours, is it "good enough"?
It was never made clear before Rhys-Davys left the show, but there was a critical clue left by the writers which Professor actually slid at the end of the episode. Wade in this episode said "I didn't know the professor wore glasses?" which implied their Professor doesn't wear them. But in future episodes, we see the Professor needing bifocals to read a book or document. This was the clue that indeed it was the other Arturo who slid. This was confirmed years later in 2009 by the producers of the show.
It was never made clear before Rhys-Davys left the show, but there was a critical clue left by the writers which Professor actually slid at the end of the episode. Wade in this episode said "I didn't know the professor wore glasses?" which implied their Professor doesn't wear them. But in future episodes, we see the Professor needing bifocals to read a book or document. This was the clue that indeed it was the other Arturo who slid. This was confirmed years later in 2009 by the producers of the show.