fought a group of elite zombies (electrified, healthlink, ..., knockback) in act 1 inferno...they appeared to be knocking each other back however, as one would go flying at me with the same animation as a knockback. They did NOT have teleport of speed, and my ping was at less than 150ms.

I was a demon hunter, so I wasn't confusing them or anything, they just liked to knock each other about.