I read somewhere else that Mr. Johnson and Simon Soundman look similar... because they are brothers.
In the sketch where Simon goes to Charlie's restaurant and orders a <bawk, bawk> (chicken) sandwich, he apparently says under his breath, while Grover is back in the kitchen, something like "Boy, my brother was right, this place/the service here is lousy." Of course, in the end, Simon changed his mind -- instead he wanted a hot <ruff-ruff-ruff....>. Notice that at the end of the bacon and egg sketch Mr. Johnson also wanted a hot dog (actually two), so they both seem to have a preference for frankfurters.