Two of a Kind (1998)

"Two of a Kind" is a family comedy with a romantic twist. Kevin Burke is a science professor and single father who believes there is a scientific explanation for everything--except how to control his scheming preteen daughters. Mary Kate and Ashley are twin sisters who are complete opposites. Mary Kate is a tomboy whose biggest interest is perfecting her curve ball; Ashley is a straight-A student starting a boy-crazy phase. Enter Carrie, a 26-year-old freshman in Kevin's seminar who has come late to college after exploring the world. Carrie is quirky, difficult, beautiful, and quick to speak her mind, so when she answers Kevin's ad for a part-time nanny for the girls, he is convinced that she's nothing but trouble. The girls think she is a dream-sitter come true and agree to put their differences aside and join forces to stir up a little chemistry between their by-the-book dad and the beautiful woman who seems to drive him crazy in all the right ways.