What will happen if I use 2 wifi routers in one room or one house. Will it confuse the computers that will connect to either laptop? Will the signal fight with each other or jammed one another? What I need to do to make it work?
Depends on how you're trying to use them. Are they each connected to their own respective modems (i.e., completely independent Internet services)? Or perhaps are they both using the same internet service (i.e., same modem) but you’re trying to chain them together to extend the reach of your wireless signal?
So thats it? Just make sure different channels for both? What will happen if both routers running on the same channel?
It's no different than if it was you and a neighbor. Assuming you were within range of each other, each would create radio interference w/ the other. It doesn’t even require another wireless router. ANY device sharing the same channel (freq.) can have the same result. Many other devices use the 2.4GHz freq as well including cordless phones, microwave ovens, radio control equipment, etc. Any one has the same potential to create interference. So you need to use different channels to create separation.