Is it possible that alduin has tried to come back, but in the form of the first dragonborn?

I doubt it. I think he's just a power hungry dude.
He wanted power, so he became a dragon priest. He learned he was Dragonborn and could dominate the Dragons. I don't think he's Alduin's buddy, or reincarnation.

This. Though he may have become a Dragon Priest to get closer to the Dragons so he could eventually devour them.

Sounds good too.

Well, they do both have very large appetites.. although Alduin's is a little larger.

This got me thinking if Alduin and the first DB ever met or even fought. Would be intersetimg if the did.

[censored].
Complete Horker[censored].
Total Mer [censored].
Fully Beast [censored].
Everything Stool and a Bucket in a corner [censored].
I think ive outdone my point!