to temporarily (until reboot) change the adb serial number, disconnect all but one of the devices and type this in a command window:

adb shell 'echo -n "xxxxxxxxxxxxxxxx" > /sys/class/android_usb/android0/iserial'

where the x's represent the desired serial number. this change requires root and will only last until the device is rebooted. to make it permanent, you'd need to alter one of the system startup scripts to make the change.

note that this doesn't seem to work as often on newer devices; the file location has apparently changed.

Related Query

More Query from same tag