I would look into it further and see if there is a common parasite that can be shared between the two reptiles. Many times parasites or diseases can be passed from feeder reptiles to their new hosts. Since eggs pass through the cloaca, it could be a possibility.

There is no problem with a baby tegu eating a chicken egg. Crack it, boil it, scramble it....I don't know of many people who just hand their tegus a whole raw oval egg.