TvMan,

A couple of suggestions, depending on exactly what you want your final video to look like:

Simplest would be to film yourself twice (camera on a steady tripod!) against a static background, say a brick wall for an easy test, first on the left and then on the right side of the view. Then in MEP put your 'left' and 'right' versions on separate tracks with an alpha mask in between. It can be just a jpeg which is black on one side and white on the other. When the mask is set as alpha mix you will see the 'left' and 'right' clips on opposite sides of the video frame. Obvious limitation is that you and your clone can only have limited interaction and can't overlap.

For more complex interactions you could film your clone against a blue or green very plain evenly lit surface. This clip would be placed on a track bellow the normal film and have 'blue screen' (or green) mix effect applied. Now only your clone appears in front -- the blue part become transparent.

Depending on your program version the alpha, blue and green mixes are on the FX window [Y] key shortcut, or on the 'Effects' tab, Video effects' >> 'Chroma key'. 

Hope this give some help,

Carl