Of course.
A quick (and not too efficient way) to do it would be,
-------------------
if(switch == 1)
{
drive_onejoy();
}
else if(switch == 0)
{
drive_twojoy();
}
----------------------
switch would be the switch, drive_onejoy() would be a function for driving with one joystick, and drive_twojoy() would be a function for driving with two joysticks
Hardware wise, you could use the throttle on the first joystick as the switch. So past the halfway mark in one direction is one value for switch, and the past in the other direction would be the other value. Let me know if this helps any
The above code is in C format btw, not pbasic.