Lauren,
I think what are often referred to as "Peruvian altums" are actually scalare, also known as Peruvian scalare. They are not altums, but a form of scalare that have altum characteristics, such as the notched forehead. If you look for "Peruvian scalare" pictures online you will probably find a lot of fish like the one you mentioned in your post. They are fairly common.
If I'm wrong I hope David or another angel enthusiast corrects me, lol.
Ryan