Two White Female Zebra Finches

Question
Since we have established that my two little whitish gray zebra finches are girls, would it be safe to introduce a male? Or, will the bond that my two have be broken forever? I do not necessarily want to breed finches.  That is not my intention at all.  I just want to hear the little song that the finches make. And I did read somewhere that 3 are better than two.  What is you opinion on this situation, please.

Answer
I would go with two males so that both have a male. Sometimes females will fight with each other for the one male. If they do breed you can just make the eggs duds by sticking them in the fridge overnight and then giving them back (careful dud eggs do rot and smell terrible when they are accidentally broken open).