You can create the illusion of the same person in the scene twice using the Chroma Key Color effect, also known as the "green screen" or "blue screen" effect. In this effect, the actor is shot against a solid color background. Video Edit Magic then makes all of the video that is that color transparent, so the other clip (which includes more video of the same actor) shows through.

We have published an article, Using The Green Screen Technique, which should be very helpful to you.