Test my Multiplayer Game Website with different IPs but only one Internet connection

I am developing a multiplyer game and i am using node.js, and socked.io on the cloud9 IDE. I want to test the game, but i only have one internet connection and two pcs. I am looking for a solution to simulate multible players with different IPs, because my game will only recognise them as different players if they have different IPs. If there is a way please let me know!

Thanks for your help.