Just out of curiosity: Did you try this on a PC?
As i believe you said there seems to be an issue with your “main” machine as the second machine told you that the software’s already installed. Could it perchance be that you’ve updated the hardware with a glitch in you main computer that made the CMC-hardware “think” it’s updated, but in fact got an error to the code that makes it impossible to overwrite… i don’t want to put salt in your wounds, but it’s better to find the faulty hardware now instead of when the warranty’s expired
The screenshots you’ve taken above of all units are they made when a single unit is connected to one port on the MAC so it’s not all units at once into a HUB?