The following actor have won two Oscars within the same category:
Best Actor: Three Oscars
Up to 2013, only one actor, Brit Daniel Day-Lewis has won three Best Actor Oscars, in 1989, 2007, and 2012.
Best Actor: Two Oscars
Fredric March Spencer Tracy Gary Cooper Marlon Brando Jack Nicholson Tom Hanks
Best Actress: Four Oscars
Only one actress, Katharine Hepburn
Best Actress: Two Oscars
Bette Davis Luise Rainer Vivien Leigh, Ingrid Bergman Olivia de Havilland Elizabeth Taylor Glenda Jackson Jane Fonda Sally Field Jodie Foster Hilary Swank, Meryl Streep
Supporting Actor: Two
Anthony Quinn Peter Ustinov Melvyn Douglas Jason Robards Michael Caine
Supporting Actress: Two
Shelley Winters Diane Wiest