Normally a website can only track and display the website visitor's IP address and not the device MAC address. When a person visits your site they are behind a router which normally uses NAT. Routers will only display the IP address. Each device on the network has their own IP address. The router can display the MAC address of the devices attached to the router, but the router will never send the MAC address out. When you check on your IP address, each IP address in your network is different. The router normally uses an IP address of 192.168.0.1 or it can be 192.168.1.1.
All devices on the router have a special IP address assigned to the device. If you have 4 devices on your router the IP address would be:
With each device, the router will assign the MAC address associated with the device. The router will display the MAC address in the setup and configuration of the router.
These are internal IP address on your network and not an IP address that is shown online. The IP address that a website sees the IP address assigned from your ISP.