The Three Lives of Karen (1997)

State trooper Matt patiently accompanies his bride, Karen Winthrop, when businessman Paul turns up and claims she's his missing wife and the mother of his daughter Jessica. He could be right, since Karen has amnesia. Evidence she was indeed Emily Riggs convinces Karen to stay indefinitely and postpone the wedding. However, digging for her past she stumbles across an earlier identity, Cindy Last, trough embittered foster-mother Lois, who hints at a traumatic start of her wandering.