Suggestions by @jameseller

Spellbound

as Best Picture 1946 in Oscars Do-over

Clarence Brown

as Best Director 1946 in Oscars Do-over

Gene Kelly

as Best Actor 1946 in Oscars Do-over

Greer Garson

as Best Actress 1946 in Oscars Do-over

Robert Mitchum

as Best Supporting Actor 1946 in Oscars Do-over

Joan Lorring

as Best Supporting Actress 1946 in Oscars Do-over

It's a Wonderful Life

as Best Picture 1947 in Oscars Do-over

Frank Capra

as Best Director 1947 in Oscars Do-over

James Stewart

as Best Actor 1947 in Oscars Do-over

Jane Wyman

as Best Actress 1947 in Oscars Do-over

Lionel Barrymore

as Best Supporting Actor 1947 in Oscars Do-over

Donna Reed

as Best Supporting Actress 1947 in Oscars Do-over

Miracle on 34th Street (1947)

as Best Picture 1948 in Oscars Do-over

George Cukor

as Best Director 1948 in Oscars Do-over

Gregory Peck

as Best Actor 1948 in Oscars Do-over

Rosalind Russell

as Best Actress 1948 in Oscars Do-over

Charles Bickford

as Best Supporting Actor 1948 in Oscars Do-over

Ethel Barrymore

as Best Supporting Actress 1948 in Oscars Do-over

Hamlet (1948)

as Best Picture 1949 in Oscars Do-over

Laurence Olivier

as Best Director 1949 in Oscars Do-over