UKHeliBob:
How are the inputs wired ?Have you got pullup resistors in the circuit to ensure that the inputs are always kept at a known voltage and not floating at an unknown voltage ?
yes i have a 10k ohm resistor as puldown on both buttons.
Delta_G:
You should allow a little time for the button presses. You're not going to be able to press both buttons at exactly the same nanosecond so the controller will always see one before the other.
where do you want that delay?