Ordinary mirrors have a smooth silvered back which reflects all the light falling on it. The plastic sheets have no silvering, so 95% of the light passes through. However, there is enough reflected light to give a “ghost” reflection from each sheet.
When you see your reflection in a mirror, your image is actually behind the mirror, as far behind as you are in front. It is the same with the plastic sheets which are at different distances from you, so your images are spaced out behind the sheets. You can make the ghosts move about by swinging the plastic sheets.
When the light hits the sheets at angle, more light is reflected. This
means that you see brighter ghosts when somebody else is in the spotlight and you are standing slightly to one side.