Dead Ringer (1992)

Identical twin sisters Margaret (Bette Davis) and Edith Philips (also Davis) haven't spoken in nearly 20 years, ever since Margaret hoodwinked the man Edith loved into marrying her instead. When Margaret's husband dies, Edith reunites with her twin -- but only to seek revenge. Killing her sister and stealing her identity, Edith has everyone convinced she's really Margaret. But when she encounters Margaret's lover, Tony (Peter Lawford), Edith uncovers a shocking secret that threatens her plans.