Ok we all realized a "flaw" that was supposed to be in the sandaime vs orochimaru fight. When a spirit in the death gods stomach cannot be summoned, oro tried to summon three people while he summoned shodaime, and nidaime, right?
and everyone claims the fourth cannot be summoned.
so here is my theory
Naruto 117 page 18 | One Manga
what i am saying is that it could have been uchiha madara.
maybe madara was supposed to be given the original sandaime title but after falling out with shodai, he didnt get it. explains why sarutobi got it when he was 13!!!
so uchiha madara was really dead so oro tried to summon him?