That's pretty normal behavior for some lizards. Babies often eat adult poop to get their gut right. In other words, they need good bacteria in their digestive tract for a healthy gut. Doug Dix, a breeder of uromastyx lizards among others, once told me that he tries to make sure all his babies eat some poop from their mom to promote healthy gut function.

This is another reason why w/c lizards can be trouble. Some have bad bugs in their guts that can be transferred to an otherwise healthy colony.