I think really it was Bert who had the problem. He should have left Ernie. Ernie was just oblivious and didn't realize there was any problem at all. Maybe Bert came from an abusive family.

When my brother was little he used to call them both Ernie. I wonder if that signifies something. Of course we had two uncles and he used to call them both Jeff. When we finally convinced him they were two different people with two different names the best he could do was to call one Jeff and the other "the other one"