Sounds like the "Two Wrongs Make a Right" Fallacy. Person 1 did X(Racism) to person 2. Therefore, Person 2 is justified to do X(Reversed Racism) to person 1.

Sounds like the "Two Wrongs Make a Right" Fallacy. Person 1 did X(Racism) to person 2. Therefore, Person 2 is justified to do X(Reversed Racism) to person 1. And of course the blatant generalization, considering not everyone behaved like person 1.