I was recently reading something that I think we in the Aspie community can use so we can pick up on the behavior of people who are two faced. I have also learned that being two-faced doesn't necessarily imply that your so-called "Friends" are talking behind your back. Rather, there are other hints that are more subtle.
1. Everything is a competition to them or they like to show off.
2. They give you bad advice on purpose so you make bad decisions because they don't want you to succeed or surpass them.
3. They say things that sound genuine but what they really doing is a form of cutting you down. EG: That's such a pretty dress and it looks good on you. Yet, given your budget, I am sure you didn't pay for it all by yourself."
4. They act like your best friend when the two of you are alone but when you are around others, they act like they don't know you.
5. They contact you when they want something and even act like they want to be friends again but when they have what they need, you are shunned and ignored. When you confront them, they give excuses
6. The famous rejecting you when times get tough.