Hi Terry,
I like the clown car analogy. I never thought that demonic possession could be funny but there you go.
I wonder if L Ron Hubbard's Scientology doctrine of Body Thetans has its origins in the Biblical account? Supposedly you can have thousands of infestations at once.
It certainly is something that Horror films have used on many occasions. When the devout exorcist asks the person possessed what the name is of the demon possessing them, I have heard the response on more than one film or tv show: "We are legion." I think its sort of a cool horror idea.
Practically though how do the demons work together? Do they cooperate like a hive mind or does one demon get the left ear, another the right foot and yet another the pancreas and so on?
Deep matters to consider.