Hillary Swank (Million Dollar Baby/Boys Don’t Cry), Sally Field (Norma Rae/Places in the Heart) and Jodie Foster (Silence of the Lambs/The Accused) are all double Best Actress Winners.
It's the same thing with the male equivalent of this quiz. It has Tom Hanks listed for his wins for Philadelphia and Forrest Gump, when a good number of other actors on that quiz have won a Best Actor Oscar more than once.