[didibus]

As a side note, you can't use the word fallacy as a synonym for wrong.

A fallacy is when your arguments don't actually prove that the conclusion is right, yet convinces people that it is. It's an error in reasoning that leads you to believe the conclusion derives from the premise, when it doesn't. It doesn't even mean the conclusion is wrong, just that it doesn't derive from the premise and arguments and as such hasn't actually been proven right.

So you should say: "It's wrong to believe you can fight discrimination with more discrimination".

Because"that X can be fought with a variation of X" isn't fallacious, this is a logical possibility. A variation of X could in some circumstances be used used to fight X. There's no error in logic here.