Hayley Mills' deception is finally figured out by her parents Brian Keith and Maureen O'Hara when they realize each has had the other twin in this clip from The Parent Trap (1961). The two Hayleys (yes, there are two of them) have tried to reunite their parents after they divorced when they were young, but Maureen is having none of it and tells one Hayley to go upstairs and pack, with a swift pat to her behind. However, is it her daughter? Neither of the two Hayleys are telling, as the parents realize they have been well and truly done by their daughters...