This is, in fact, a big problem in medicine. When I was in medical school there were a good number of students in my school who were there as a result of affirmative action. A significant number of them could not pass the required tests to graduate to the next level, and so they would have to repeat the curriculum, some as many as four times. Other students who were admitted strictly on merit would be booted in a similar situation [although most- not all- would be given one chance to remedy their failure].
A friend of mine had a funny solution. All those who believe in affirmative action should be served by physicians who graduated due to affirmative action.