G4 dual monitors?

Hello all hopefully someone can help me here... I have a g4 and i have to monitors hooked up to it on one video card... I have to different types of monitors on there...b/c on the video card there is 2 slots...and since i am at a school i can get more than one monitor...anyways when i hope them both up and restart the computer all i get is one that displays the image. Now my question is.. is it possible to hook up both of them on the same video card, and if so where do i change it. bc i looked in system pref. and under displays and it didn't list the other monitor any where...also i have both monitors turned on when i boot the computer so it should work...hopefully someone can help me out! thanks
justin Reynolds

To help you out, a little mor information is needed...
What type of G4 do you have (if it's a stock graphics card) or which graphics card is in it (if it's not stock)?