In a terrifying scene from Revolutions, it's shown that he can also do this to people who have been disconnected, allowing him a gateway into the real world.
In The Prestige, Angier uses the Tesla Machine, an electric duplicator/teleporter to create a perfect copy of himself to perform his "Transported Man" magic act. It's never established if the copy is created a distance away from the machine, or if the original is teleported but an exact copy is left behind. Since the trick involves killing the one left in the device, Angier never knows if he's killing an exact copy of himself for the trick, or if he kills himself each night and the copy continues on.
In Asterix And Obelix the Druid multiplicates the eponymous duo to repel the Roman invaders.
Penny the cheerleader in Sky High (2005) is the entire cheerleader squad. She ultimately turns out to be one (or several?) of the Big Bad's allies.
Being John Malkovich: There's a door into John Malkovich's head that allows people to see through his eyes and (with experience) control him. When Malkovich goes through the door himself, he finds himself in a room where everybody has his head (including the women) and can only utter "Malkovich" to communicate.
In Resident Evil: Extinction, Alice, teams up with a large number of clones of herself, with the intention of going after Umbrella.
In Monsters vs. Aliens, Gallaxhar's evil plot turns out to involve creating an army of clones of himself to conquer the Earth.
In Cult of Chucky, it turns out that Chucky has learned how to copy his soul onto multiple bodies at once. In addition to the original, currently held prisoner by Andy, he possesses three other Good Guy dolls over the course of the film, and ultimately Nica as well. And it turns out that he taught Tiffany the same trick.