FWIW, I see similar behavior on a 2017 MBP running with 10.15.6 or 11.0 (Big Sur) beta 4. That's ... odd that there is a non-unique MAC address. (Not surprisingly, there is no such problem on an iMac that doesn't have the touchbar subsystem.) That particular interface doesn't show up in the user-visible Network panel of System Preferences so it can't even be easily reordered there.  I suppose there is a good reason why it appears at the top of the interface list but, yes, we don't want to be using a non-unique MAC address to generate UUIDs. The question then is: is there any way for the uuid module to recognize and ignore such interfaces other than by the hardcoded MAC address?