Ethernet, and wifi is disabled. But even if it was wifi or another network interface getting the IP, I should have been able to find it in ip a / ifconfig I'm assuming
Maybe I misunderstood what you wrote, but you feel the traffic is actually originating from your desktop? I am completely unaware how someone could get 2 IP addresses for your desktop without that showing up somewhere on the box (agreed, you should have found it with the tools you ran). I still think wipe and wait, but this seems like you got seriously hacked. Good luck.