OK I admit it I was wrong the 2nd isn't Tobi because I just realized something from reading it again.
Tobi is a Zetsu clone because when Madara is summoned he talks about Nagato & how he's grown I think Madara thought that Nagato had summoned but then Muu tells him he was Edo summoned. & remember back when Zetsu told Tobi that Nagato used the Rinne Tensei Jutsu to bring back the people he killed in Konoha Tobi said that Nagato was suppose to use that on him I guessing he meant the real Madara.
Tobi is a Zetsu clone because when Madara is summoned he talks about Nagato & how he's grown I think Madara thought that Nagato had summoned but then Muu tells him he was Edo summoned. & remember back when Zetsu told Tobi that Nagato used the Rinne Tensei Jutsu to bring back the people he killed in Konoha Tobi said that Nagato was suppose to use that on him I guessing he meant the real Madara.