I believe that there is a difference on a Pi4 with USB version types. But I never had one to test that local.
I still suggest putting one of these on the other USB header so it is addressed as 2-x:1.0
That is the format the software is expecting. No matter what the OS reports.
When the software was written, the Pi 4 was not among us yet.
There have been strange issues here and there with 4’s, but I have not read or herd anyone with his one.
But generally, I have seen issues when they are on the same header on 3/3b’s
Unknown causes. But not all of these chips in the sound fob are exactly the same.
So, we can wonder and try to work around them.
But the first number is the USB header and the second is device# on that header.