Same. Cat doppelgangers are a regular nightmare scenario for me, go figure. I thought maybe it was something I picked up from the Matrix.
I always thought of it as a lesson to be learned. Don't trust people too easily, be able to recognize the false people, and when you do recognize them, make sure they don't do more harm then they already have.

I used to have problems with trusting people too easily so it could stem from that for me.