When I clone a windows VM - whether a linked clone or a full clone, the resulting VM has the same mac address (from the Operating system's perspective) as the original VM. Parallels is reporting them as having different mac addresses...but the OS shows the same mac address as the original VM.
I have isolated this to being an issue with the "Intel(R) Gigabit CT (82574L)" network card. Changing to "Intel(R) PRO/1000 MT" works just fine.
It doesn't look like it's the card...it was happening for me on the "Intel(R) PRO/1000 MT" card as well. The issue seems to be addressed by *changing* the network card from the one the OS "thinks" it has. I think that somehow "kicks" the OS and tells it to look again at the MAC address.