i am not sure you can have 2 diffrent player using keyboard inputs on SFIV, it is either player one or player 2, i might be wrong though, if i am the guy above gave the answer, just don’t map the same button for both players and everything will go fine.
also don’t cheat since you will basically have control of both character on both keybnoard as he said, no matter how many keyboard are plugged on the computer the game can’t make them out from one another, unlike it does for gamepads.
on a side note you could use a third party program that records keyboard input and use them to emulate a stadart gamepad.
Also last tips
-playin sfIV on a keyboard is really bad for your wrist’s sinews.
-You should also be aware of the fact that the one using the ps/2 keyboard is going to have an edge over the guy using the USB keyboard (unless it is one of these Razer overclocked polling keyboard)
-don’t play zangief with a keyboard, i am serious, if you really want to you might want to think about mapping jump to something you can hit with you thumb like the space bar