Hello Edgar,
> Is there any way I could use that value to differentiate between them?
> 
> I cannot change bus, this is on a raspberry pi
have you tried to run 'nut-scanner -U' to find out the serial
number of the UPS, so that you can use it to identify each
device:
# nut-scanner -U
Scanning USB bus.
[nutdev1]
        driver = "usbhid-ups"
        port = "auto"
        vendorid = "051D"
        productid = "0002"
        product = "Back-UPS BR  800 FW:9.o4 .I USB FW:o4"
        serial = "3B763X76344"                             #
<<<
        vendor = "American Power Conversion"
        bus = "002"
This output would mean that you need to add the following entry
to your configuration:
serial = 3B763X76344
Regards
Juergen