Detecting mulitple xbox controllers on Windows - randomly gets joystic number.

In our game we are having an issue with Xbox 360 gamepad. When using more than one Unity detects them not always in the same way. Sometimes gamepad marked by a light as 1 is detected as the joystick 1, sometimes as joystick 2 or 3, or 4.. etc. It messes around when we have only 2 players enabled and buttons for controllers are mapped as eg. Joy 1 Button A (joystick 1 button 0) and Joy 2 Button A (joystic 2 button 0) and unity set up controller to be a joystick 3. Does anyone knows how to resolve this problem?