2 mics on 1 computer?

I want to use two mics on a single computer for a buddy and I to do live shows with, my computer does have two microphone inputs but it only recognizes 1 mic at a time. As in I could have them both plugged in but only one will actually record any type of sound. No I will not buy a splitter. There has to be some kind of software that can help me out here. Any suggestions?