User blog comment:Master Sima Yi/Assassinews 19-03-'14 – Two Assassin's Creeds for 2014?: Unity and Comet/@comment-4928711-20140612183744/@comment-5174994-20140612193534

Right at the beginning of the co-op demo, when he enters the first building, you see him stab two guards at the same time. This doesn't instantly kill the one on the right, so he stabs him again. I'm quite sure that this was just for a cool animation, not because he doesn't have a second hidden blade.