Emulator Problem: EPSXE wont let me hold 2 or more buttoms simultaniously in a game. How do I fix this?

[GuyVelella]

Im playing Driver for PS1. To look back I need to hold both R2 and L2. When I hold L2 while driving I see left, holding R2 I see right. They work individually. Nothing happens when I hold them together. Everything else works. All the inputs are set up right. Im using a dualshock controller. Whats causing this problem and how could it be fixed?