I have had 2 house finch couples fighting over an old nest. 1 of the females have re-built the old nest.?

best to start over and just get two new nests and try to put them into different spots than they were in then there will not be a problem-Don't worry at some point you will have more finches than you know what to do with-I used to have them but I didn't mix mine up once I found homes for the first brood.