This is a different problem. Each object has pre-defined slots for interaction between sims, operator(s) of the object, and the object itself. When this problem occurs, as many as five sims will share a slot which means they'll stand within the same space during the interaction. They're not passing through each other, they're being routed to identical locations for random interactions. in extreme cases they even stand at the DJ's position facing the opposite direction after passing through the walls of the DJ booth.