Von Haut zu Haut (1970)

In the middle of the night, Nicki is once again haunted by intense feelings that she can't explain. A visit to the doctor is supposed to help and behold: the more he pokes around in the past, the more a connection between Nicki and her twin sister Karen becomes apparent. In addition, the two ladies are each pursued by a menacing man who roams the streets late at night with a knife and seems to be in cahoots with an oddball antiques dealer.