two at2560 via maxuino.

Hello everybody,

I'm trying to connect two at2560 via max/msp/maxuino, but I desesperatly can't achieve the stuff.
I've max 5.1.

When I connect both of the arduino, I've got two different ports in maxuino, but even if I choose the
first or the second ports, it's always the same car which works. The second is passive.

If you have any solution, would save my week;

thanks.