No, that translation was a poor one.
Tobi, pretending to be Madara, was saying that he (Madara) obtained Hashirama's powers, and became the second person to unite Uchiha and Senju powers in one being (meaning, his body possesses both Uchiha and Senju powers); and therefore, he is the only person that can carry the title of "Futarime no Rikudou" or "Second of the Six Paths."
Since Nagato bears the Rinnegan, and thus Uchiha and Senju powers, he is the third person to carry the title of "Rikudou" - he is the "Sanninme no Rikudou" or "Third of the Six Paths."
Basically, only those that obtain both Uchiha and Senju powers carry the Rikudou title, Rikudou meaning Six Paths. It's suppose to signify the order in which someone obtained the Rinnegan. The original Sage of the Six Paths was the first Rinnegan user, Madara was the second Rinnegan user, and Nagato the third - Obito became the fourth after the plucked Madara's eye from Nagato's corpse.