I have also only heard of the one. I think Steve may have posted about this one a while ago, that's the only reason I know of him/her. The Bullen's did have two but after the problems with mareeba they are now at mogo.
The very fact that someone who owns a chimpanzee gives it a stupid name like Mr. Muggins or Wally Muggs or whatever makes me cringe.
It's proof that the dignity of the animal is not being respected.