Wow, I have never read about a Cham eating his own shed... I know some species of geckos do and have seen my Crested and Tokay geckos do it. Sorry, don't know what t tell ya' other than it's gross thinking about eating your own shedding skin, lol!
It's pretty common. I suspect it stems from a desire to hide his presence. Nothing says "hey, there's a reptile around here" like a big hunk of shed skin.