Anna's movements stopped when she heard the names of her and her brother from the old man. "Coleman? Me and my brother?" Anna scoffed. "Heh. If I were Anna Coleman, do you really think that I'm willing to be here in this damp place?" Anna tried to play it cool. She doesn't want the old to think that what he said is facts.
Since the public already knows the Coleman twins' faces, it is possible for the old man to recognize them. However, on the way here, Anna and Aaron overheard that this old man has been in this room for years, and getting pictures of the Coleman twins outside of this building is impossible for this old man to have.
In other words, this old man has been away from society and has no idea of the twins' figures and faces. Anna is confident that the old man is only talking nonsense, he doesn't have the evidence that she and her brother are really are the Coleman twins.