You are correct, the TIU's should not have the same address, that really confuses things. The remote ID apparently doesn't really do anything as that's never been a factor. I think it was intended to have some function that never happened, but that's just a guess.
Right now with my temp track and my workbench, I actually have two TIU's that are both #1. I don't use them at the same time. However, I occasionally forget to unplug the USB to the computer on the bench TIU, and when I try to run something, I get all sorts of no engine, can't find engine, etc. until I unplug the USB.