How to distinguish between two devices with identical PIDs in MAME

[TEC75]

Hello!

I've been trying to determine how best to configure my cabinet to work with both MAME and Retroarch.  My current iteration is using an I-PAC Ultimate in mixed mode (firmware that allows both joystick controls and keyboard controls in the same config). 

The "why" is a long story, but here is my problem.  The I-PAC controllers appear with only a single PID, so I have not been able to distinguish between them in MAME via the ctrl remap function. 

 

Below are the full device Ids as MAME reports them.  There is a subtle difference in bold.  I have tried using this entire string in the ctrl remap file.  The logs show it remapping, but the mapping doesn't actually change (Joystick 1 is still player two, and vice versa)

1. I-PAC Ultimate product_0410d209-0000-0000-0000-504944564944 instance_cb298f50-da88-11ee-8001-444553540000
2. I-PAC Ultimate product_0410d209-0000-0000-0000-504944564944 instance_cb2b3d00-da88-11ee-8003-444553540000

Retroarch seems to be able to tell a difference, or at least labels the controllers as if it can tell a difference - displaying them with a (1) and (2) suffix.  But when saving the controller config file, they end up sharing a single config file so I cannot set different button configs for player 1 and 2.

 

Here is the only guidance I could find via the Ultimarc site:

This is an alternative firmware version which enables the board to appear as a keyboard and dual standard game controller AT THE SAME TIME (both also with mouse). Note Retropie does not work with this configuration. The standard multiMode version (above) enables one device type at a time on the host (plus mouse) and this is required for Retropie. IMPORTANT: This version also requires a different version of WinIPAC for configuration.
This version does not support Xinput.
Unlike the Multi-Mode, this version automatically allocates each of the 2 game controllers on the respective side of the board so WinIPAC does not refer to player numbers, these are defined by the board markings. 

If what they mean by board markings for player 1 and player 2 are the button numbering, I have that wired correctly, but the opposite controller is active in MAME.

I've not been able to find any other references to how to distinguish between the two controllers programmatically, and have found no other references online.  Does anyone have some insight they could share on this?  TIA

Edited March 5, 2024 by TEC75
typo