Here's the INI file that I'm using, which coincides with what the program detects:
mameconfig version="10">
<system name = "default">
<input>
<mapdevice device="PID_1603" controller="GUNCODE_1" />
<mapdevice device="PID_1604" controller="GUNCODE_2" />
<mapdevice device="ATRAK Device #1" controller="JOYCODE_1" />
<mapdevice device="ATRAK Device #2" controller="JOYCODE_2" />
</input>
</system>
</mameconfig>
In MAME, after reboots, the GUNS ID in the game jump from GUN2, to GUN3, to GUN5......driving me nuts!