Herichthys cyanaguttatus certainly does change to dark and light, from front to back, just like H. carpintis.Carpintis also turn black and white when spawning and Texas cichlids do not... So now this is why ppl get confused on fish..
People confuse the fish because they are very closely related and look similar. They share the same common name because of their similarity. Just like numerous other common names that refer to more then one species such as crocodile, zebra, elephant, and giraffe.