Question about the sister segment

I remember seeing a movie when I was a child that scared a crap out of me. I can only rembember bits and pieces of it but I was wondering if it was the sister segment of Trilogy of Terror. What I remember is there were dark haired sisters who were actually siamese twins that were hacked apart at the hip with a meat cleaver. I remember one of them holding a bloody butcher knife and at the end one of them was dead and folded up in a sleeper sofa and left on the side of the road somewhere. Is that what this was, and if it wasn't can somebody tell me what movie it is that I remember? Thanks, Raye