In DN, inside the houses, when a draclic pops, the halfway down the ground. When some mobs run, they also half way they halfway in the ground. In CS, when exit the tunnel from cs into what was SG, there shark sticking out the wall. Seems the surfaces are not defined, allowing mobs to sink into the walls/grounds
In DN there the skeletons with the ribcaves, traps where the dracoliches can pop, there 3-4-5 op top of each other. And I think you can get unlimited if you want, not willing to test that.
The zone geometry is not the same as the original zones. I bet they didn't update the pathing of the npc's.