My network scanner shows a fake mac address for my imac

My iMac has been behaving strangely regarding the internet and network connections.

So I started up IP Scanner Pro and got a listing of all devices on my network.

My iMac shows up multiple times in the list:

1. The ethernet connection shows up with the correct MAC address as shown in the system info

2. the wifi connection shows up correctly using the same comparisons.

3. However, a third (and sometimes 4th) IP address shows up with a MAC address that is nowhere to be found in any of the system information.

I am running Yosemite 10.10.3

I am NOT running Parallels or any other virtual machines

I have just reformatted my hard drive and done a clean install and then restored my user (not system and network settings) and data from Time Machine.

All apps have been installed from scratch.

How is this possible?

Any ideas?

Thanks

Peter