i agreei think its madara's brother too ... you see when minato saw tobi's true face he thought it was madara but he could be easly mistaken because they are brothers after all and minato cant know exactly how madara looked so his opinion was based on what he has heardand kabuto summon madara's body and thats why Izuna agreed on alliance because he doesnt want his little secret to be known by all because that will ruin his plan to some point
A lot of truth in that statement.He sealed chakra into himself and yes the numbers do mean something.
The first coffin had 1 on it for the 1st hokage.
The second coffin had 2 on it for the 2nd hokage.
The third coffin had a 4 on it for the 4th hokage.
Anyways im not gonna argue it can be whatever anyone wants it to be. The point I wanted to make was that If Kishi wants it to be the 4th then it will be the 4th nothing anyone can do about it.