She's a borderline, it's her way of coping with a break up. She will get a guy that looks/acts/feels like you but a lot less work for her, an easier mark. Let it happen. Also it's not weird for them to date someone that looks like you, it means a couple of things:
1. She isn't over you, even if she won't admit it
2. She's looking for you in another guy but easier to get and to mold to what she wants.
3. She's not taking the time to re-evaluate herself after her breakup, so if she came back to you
she would be the same
Had the same thing happen to me with my current ex, she started seeing several guys (pathetic looking I might add) and playing the field, taking pictures on facebook during our "break" and breakup. Didn't last but a month if not less with all of them.
http://gettinbetter.com/anycost.html
Read that link, will help you immensely, and will probably describe your relationship you had with this so called woman.
I'm just wondering why he didn't cut her out immediately.
Day 121.... I think
Haven't looked at her FB in about 2 weeks, found out I'm going on another engineering trip to represent our company in developing a prototype for their engineering systems.
Sometimes I do miss the intimacy we both shared, but I remember all the crap that came along with it. I can get it else where, and have been getting it else where. Who knew money/leaner muscular body/good guy additude would get beautiful women, lol.
I should thank my ex but that would mean she played a role in my success and that is far beyond the truth.