Looks like they got the rows transposed. The people in the middle have different eyes and mouths, people in the bottom have different contouring, and the people in the top have different vertical spacing.
Also, if you can do Magic Eye posters, do it here. The eyes of the people in the picture go all weird.
Alas, I've got my own funny vision, and can't do Magic Eye. Looks like you're right about the rows though.