Two IPs, two boxes, same NIC MAC?

Two ESXi hosts
both with static IP addresses
an IP scan on the Microtik router correctly identifies the IP addresses
but shows them as both being on the same MAC address.

How can two seperate physical boxes with static IP addresses report back as having identical MAC addresses? Where would this misinformation come from.

The ESXi on both servers reports different MAC addresses, the Mikrotik is running its own OS so nothing really points back to any kind of Windows error (in my thinking at least)

Any ideas? I'm totally baffled right now

 

Bit of an update.
ESXi reports a MAC ending in 5f
The router says the MAC ends 6A
vSphere also says the MAC ends 6A
but 6A is what the MAC is of the other box
(and yes I double and triple checked)