air stop detect other gamepad after detect a xbox360 controller

if I have 1 xbox controller(let's call it 'X') ,and 3 other gamepad A,B,C

using flash.ui.GameInput

if I plug the controller order in: A X B C

it only detect only return A and X, where are B and C?

but if I unplug X, it detect B and C immediately

Is it a bug?