How to find MAC Adress of second system?
A media access control address (MAC address) of a device is a unique identifier assigned to a network interface controller (NIC) for communications at the data link layer of a network segment. In other words, the MAC is independent of the operating system.

With certain hardware (such as routers), it is possible to assign your own Mac address. This is often referred to as cloning. I do not believe this is possible with macOS. Although, you can assign a your own MAC address to any virtual machines running in VirtualBox.