Frank Oz was Bert, as well as Miss Piggy and Fozzie, and Henson was Ernie, as well as Kermit and a producer on the Muppet Show. I think they had enough to do on

Frank Oz was Bert, as well as Miss Piggy and Fozzie, and Henson was Ernie, as well as Kermit and a producer on the Muppet Show. I think they had enough to do on the show as it was. Also: Oz was better at doing different voices than Henson. I think Ernie and Kermit in a scene together would be bad, since the voices were so similar.