Yeah that's what makes them special. Every one is different. No way could Jay make them
exactly the same even if he tried. Especially when doing hundreds of them.
There are more differences than you realize in those examples you posted. For instance with the Dums guy, the hat has 2 vs. 3 stripes, their ears have a different inner squiggle, one chin is more chubby, 5 vs. 7 eyelid stripes, one Adam's apple higher than the other, etc.