Disconnected (1984)

Contrary to initial appearances, a great freedom can come from being a twin. Sure, there are all those formative years being trundled off to family and church functions decked out in identical garb to your mirror-image sibling, having to assume an identity as one of two, locked into a dual persona that cannot be easily shrugged off. But once an identical individual reaches the age of unreason, that person may (or may not) commit any abomination that comes to mind and affix the blame to his or her womb-mate, the so-called evil twin. The look-alike sisters of Disconnected (1983) have been implicated in a series of bloody murders. Maybe one of the girls is involved, perhaps both, conceivably neither.