Resemblances are everywhere, especially between old movie stars, in my opinion. Because most people disagree with me, I probably don't have a good eye, but I still hope to find someone who believes Jimmy Stewart looks like Ingrid Bergman. Here are some more realistic lookalikes.
Montgomery Clift and Henry Fonda
Vivien Leigh and Ava Gardner (slightly)
Elizabeth Taylor and Vivien Leigh
Jean Simmons and Vivien Leigh
Grace Kelly and Gene Tierney
Deborah Kerr and Rita Hayworth
June Allyson and Gene Kelly (poor June)
Tyrone Power and Jim Backus
Others, not pictured, maybe coming someday: Gene Tierney and Lauren Bacall, Tony Curtis and Joan Bennett, Vivien Leigh and Hedy Lamarr, Hedy Lamarr and Joan Bennett, Jayne Mansfield and Diana Dors, etc.
Who do you think looked alike?