Bip Bippadotta is basically Mahna Mahna Version 2.0. Mahna Mahna had existed prior to Sesame Street and they brought him on to do the classic routine for Sesame's first season (though he was a weird looking anything Muppet on this appearance.) Then they had Mahna Mahna sing more songs in the 70's - this time with a closer look to the original puppet (with the green vest and all) but it was still an anything muppet made to look Mahna Mahna-ish. Then as a bonified Muppet classic, they had gave Mahna Mahna the honor of being one of The Muppet Show's first opening numbers. (This time with the original puppet). Mahna pretty much became a "Muppet Show" Muppet at that point. Since with the exception of Kermit, they didn't want to do a lot of crossovers between Sesame/Muppet Show characters, in the late 70's. they redesigned the Sesame version of Mahna Mahna (same overall basic look with the main difference being big sunglasses instead of eyes - the mannerism and voice remained the same) and called the "new" character Bip Bipadotta. So it's basically the same character redesigned. The best way to differentiate between Mr Johnson and SImon Soundman is that Simon has black hair and Mr Johnson's is brown.