Multiplicity image is a photography technique in which the same person is photographed from different point of view and directions and then the bunch of photographs are digitally re-mastered in Photoshop showing clones of the person doing different things all in one photo.
Take a look for some samples below.
This Video series will explain step by step how to create a multiplicity image using Photoshop
You can get a friend to help you take each picture, use a remote, or use the self timer feature on your camera. If your friend is pushing down the shutter button on the camera, make sure they are careful on keeping the camera perfectly in place and not to accidentally bump into it.