USB Host Shield Miscommunication with Arduino Mega/UNO

I am trying to control two independent robots simultaneously using two Arduino Mega with USB host shield and xbox 360 wireless controllers (2.4 Ghz dongle). But I sometimes face the issue where the xbox controller disconnects and connects to the wrong host shield arduino mega. Is there any way to permanently write the address of the xbox 360 dongle, so it doesn't connect to the other one. I am new to 2.4Ghz wireless/USB host shield and not sure how the address relocation works. Can someone help me out, who has worked on USB Host Shield before.