it is possible that he split his soul. for example, he could have had half his soul sealed away--a half which currently resides in Tobi--while the other half went to the "pure world." I'd totally buy that. it could have been part of his plan to live and later become whole via his young body... I'm growing more attached to the idea that they are both Madara. Also, how does Madara know about Nagato? And when Kisame had his brain infiltrated, he saw Madara controlling the Mizukage/3-tails jinchuuriki. I think that was definitely Madara cuz he had the hair and the weapon, also Itachi's flashback to when he met Madara it was definitely Madara... Yeah, they are both Madara somehow