Question device with same mac adress and same name than my router connected

[rookie191919]

Hi everyone i find this morning that there is a device connected to my router with the same name and mac adress than my router and an ipv6 ip , i dont have the knowledge to figure this out and i am afraid that it can be a hacker . i have been hack 2 years ago thats why i am afraid right know. can you guys help me there is 3 creenshot

https://imgur.com/a/fqF7h7t

View: https://imgur.com/a/fqF7h7t

 

[Ralston18]

What model SagemCom Router?

Are you using both wired and wireless network connections?

How many connected devices?

On your computer run "ipconfig /all" (without quotes) via the Command Prompt. Post the results.

Likewise run "arp -a" and post the results.