Question : Problem: Trying to Understand MAC Address with a VM Machine

How does a VM machine change the MAC addresses on a single NIC?  Does the NIC have multiple MAC addresses at any given time?  Is the VM swapping out MAC addresses based on the needed address.  Or, does it work some other way?

Answer : Problem: Trying to Understand MAC Address with a VM Machine

Remember that the VM does not have a physical NIC.   You may have mapped the virtual machine's virtual NIC to a physical NIC - but in the virtual machine it's just software.   The physical NIC on the machine just acts as a switch and forwards the traffic.   Thus the MAC address for a VM can be whatever the VM wants it to be.