Multiple MAC addresses are common for routers. For example, if you can separately use more than one WiFi frequency band, i.e. 2.4GHz and 5.0GHz, then they will have separate MAC addresses and IP addresses.
Your PC will be connected to the router using WiFi which is why you can see both. My PC is cabled so I only ever see one address for the router and cannot see the WiFi addresses.
The main reason for blocking either of the addresses is simply to see what happens to confirm which features are available at each address. This is also useful to diagnose misconfiguration which is another possible, but I think unlikely, cause of multiple addresses.
The various router addresses will not normally be included in the list of devices attached to the router because they are not separate devices. The IP addresses for the router are normally defined in the router defaults or other settings.