That's not new. In 4e his two headed nature was said to be a result of fighting with a good during the Dawn War who cleaved his head in half. But they regenerated into his two heads and then he killed the deity.
This was before he gained is title of Prince of Demons so this happened untold ages...
I liked the Psionic UA with Psonic Soul and the Psi dice and the feats and such that activated off of it, much more then what we got here.