whatttt?? so you are saying madara fought hashirama twice?
No, listen closely
Madara's Edo Tensei looks like he died in Battle (battle suit still on, like how Hidan was broght back without a mask, you are brought back the way you were last)
SN: Im eating noodles.. lol:lili:
Thus he could only have died in battle (since tobi is obviously not Madara, that i can swear to) the only battle that could have killed him would be against Hashirama (Hashirama IS kinda kickass). When Kabuto reffered to his PRIME, he meant Rinnegan, even madara's reaction showed he had attained rinnegan, thus what ever Kabuto edited in him is yet to be known(kishi just doesnt give out his plots like that)
Here's strong proof that he used Rinnegan to faced hashirama, He had attained MS along with his brother and took over Uchiha clan, then he took his Borther's eyes and gained EMS, before joining forces with The Senju to form Konohagakure. Later he leaves the village and returns some years later to battle Hashirama. I believe he gain Rinnegan during that period and Faced Hashirama (who might just be super kickass)
SN: i use side notes just to lighten up the talk, lol

Thus, he had his Rinnegan before he died and was brought back with it....
SN: obi, is probably just another uchiha who has lived for a while
Am i clear?