As I've admitted before, it wasn't until AOTC came out on DVD that I learned that they were the same person. I mean, I knew that Palpatine was the badguy who would become the Emperor, but I assumed black-cloaked guy must be some Sith Predecessor. I mean, yeah, it just seemed too obvious that they were the same, so I assumed black-cloaked guy must be a different character with a hidden backstory, maybe to lure Palpatine to the darkside as Palpatine would later do to Anakin. So much for giving Lucas the benefit of the doubt...