Zend certified PHP/Magento developer

Can someone explain my 3 MAC addresses on my router modem

I have an odd issue. On my netgear router/modem admin page I have 2 MAC addresses with last letter difference one is an A the other a B. But on my bridge router connected to the netgear one I am seeing a 3rd MAC address with a 9 at the end and the IP address points to 192.168.0.254. I know netgear has a default login at that address, but my login page is always 192.168.0.1 and the 254 one never works.

Is this normal and not some phantom device use a fake MAC connected to network