My Dad, when watching TV, would always say that a certain actor or actress looked "just like so-and-so" or ask "Who does that remind you of?" or "I know I've seen her/him someplace before". He would also say these things after meeting someone new or seeing someone in the doctor's office, etc. I think it came to the point where 1) everyone looked familiar to him even though they weren't and 2) he wasn't able to recognize faces, people, etc. His brain was not properly functioning. This sounds like the same thing that your wife may be experiencing.