How many people: explanation (thanks to Peter Hearty)
It works by slicing half-way through various body-parts and then
reusing them as two separate sets. If you cut out the sections in the
attached document with scissors you'll see that the woman on the
extreme right's legs get split in two and become two sets once moved.
Similarly the head of the guy on the front row, 2nd col from right,
gets split (his eyes being replaced with hair only from the guy at the
extreme left). Feet come from the guy 3rd from left, shorts from guy
5th from left.