Yeah, they were a broadly similar type, but clearly different women -- the subway victim was a lot more beautiful, IMHO. I'm generally not that great with faces, but I had no trouble seeing they were different people.
Besides, the plot depended on Callie not disappearing until some days after the subway incident. If she'd disappeared at the same time, that would've instantly thrown suspicion on her breakup video, because it wouldn't have fit the timeline. So they had to be two different people.