Complex sentence: Although these two earliest depictions of Cerberus show a single head, in Attic vase painting, Cerberus usually has two heads, while in other art, he is usually three-headed.
Split into simpler sentences: Although these two earliest depictions of Cerberus show a single head, the number of heads depicted in art varies. In Attic vase painting, Cerberus usually has two heads, while in other art, he is usually three-headed.