Board Thread:Theories and Speculation/@comment-26388300-20150612203442/@comment-3568954-20150613052525

when ocochimaru summoned them they were in complete awareness they understood him there personalities were not wiped away  not yet atleast. its also possible that tobirama did not know that you could rescind the contract, madara might have gained the scroll with the edo tensei on it and then fiddled around until he figured it out