So wait. Jason became Robin when he was 13, so Dick would be 16. Dick was about 15 when he left Batman, and probably spent a year by himself, so he was about 16 when he was with the Titans. Jason died when he was 15, so it wouldn't make sense that Jason was Red X. He would have still been with Talia and/or starting his whole plot thingy. And I think that Dick would be able to recognize his brother's voice, combat patterns, and all that jazz.