The way I heard it, you get a second joke in there.

One day Quasimodo asks his boss for a vacation, and the boss says “no no, Quasimodo, you are too important — people come from all over the world to see you ring the bells. If you go on vacation, what will we do? No, the only way I can let you go is if you find someone who looks exactly like you, who can ring the bells while you’re gone. And where will we find anyone who looks like you?”

Well Quasimodo is depressed, and after work that night he goes out drinking in the Latin quarter, and suddenly he sees this guy who looks exactly like him! They could have been twins. So he rushes up to the guy and explains the situation, and begs him to stand in for him as a bell ringer. And the guy says sure, anything for a fellow hunchback. So they go back to Notre Dame, and Quasimodo says “okay, now I just have to show you how I ring the bells.” And they go up to the tower, where there’s this big bell, and Quasimodo says “now watch this.” And he takes one step back. And then two steps back. And then he runs…. jumps… BAM! Smashes his face right into the side of the bell. And it goes BONNNG! And he turns to his double and says “okay, now you try!” So the new guy says “well, all right.” And he takes one step back. And then two steps back. And then he takes a third step back, and he steps right off the edge of the tower and falllls allll the way down to the pavement below and is struck stone dead. Everyone in the street starts screaming, and a policeman comes running, and he sees the body. And he says “does anybody know who this is?” And a bystander says “no, his face doesn’t ring a bell…. [pause for laughter and/or groans] but actually, come to think of it, he’s a dead ringer for Quasimodo!”