Can agents walk on top of each other?

Hi everyone,

As the title says, can agents actually walk on top of each other? It would actually be useful for one of my projects.
As an example, take the zombie swarms from the WWZ game (check at time 2:46 in this video):

Here sometimes they simply climb on the net, but they also do walk on top of each other in the game to make human pyramids of some sort.

Thanks in advance