let's not forget that in early christianity, before the orthodox roman church established its superiority, there were dualistic sects - the gnostics, for example - who believed that the devil was actually the "other" god who created the world and all that is in it, while God, the Almighty, created the soul. this placed man in the condition of having a good soul, which would hopefully retrun to God upon his or her death, but was trapped in an evil body while living in this material world.
is it possible that the depiction of the devil in the tarot which shows the devil with two "heads" - one on his shoulders and one on his belly - or both the male and female genetilia is actually refering to this dualist theme? are there any other depictions of the devil before these tarot cards which show him with these images? if not, then maybe we should ask ourselves why these images were used in the tarot card.