Remember when Tobi was about to take off his mask to reveal his face to Sasuke to prove that he was Madara? Wouldn't that mean that he would had to have had Madara's face? Sasuke should know who Madara looks like. He was the poster boy of the Uchiha after all. Also, the 5 kages were able to identify Hashirama's face on Madara's chest. Tobi even shown his face to Kisame to prove to him who he was.