Mac Address and Linux Live
When you connect to the Internet with a Live CD or Live USB, your connection to your router will create its own network ip address and use the mac address based on the hardware that is used to make the wifi connection. For example, after booting Live Ubuntu, Live Kali, or another Live Linux distro, you will make an Internet connection. If you use a wifi dongle to make the Internet connection, your router will use that as the mac address for your machine. Meanwhile, if you used the built in wifi network adapter, the mac address would be something else.
To test this for yourself, you can connect a second wifi dongle and boot your Linux live distro. Then, connect to the internet with either of your network adapters. Now, open a browser and login to the router. You should be able to see the ip address and mac address for your pc. Now, disconnect from the network adapter and connect with the other one. Now, you will see a new ip address and mac address for this connection.