Come on! Generally one of the voices you hear on the radio in a two man show, does most of the character voices. Case in point: Hudson and Harrigan. Hudson does the voices while Harrigan plays the straight man. Hudson would play the straight man as well and change quickly to any given 'bit.' (For those of you who do not know what a bit is, it is a comedy routine. ) Now, with the help of digital recording and editing, one can create a multiple voices a whole lot easier than in the past of the 'cutting block.'
Back when I was producer of the H&H show, Harrigan ran the board! He ran it because he wanted to exercise control of what was happening on the air. Plus, he would do it flawlessly. At that time, the only other person to run the board was me. Even with a producer running the board, both of the personailties have a lot to do. Believe me, Walton is working. It doesn't matter if you like them or not. It doesn't matter if you don't like their show. What does matter is that they work together as a team.