Are you running any virtual machines on your desktop? Because "My machine is 10.0.0.2 but there's something on the same physical host communicating as 10.0.0.3" is what it'd look like if a virtual machine with a "bridged" ethernet interface got its own IP address via DHCP and talked to the Internet.
This is speculation, I don't know whether you were owned.
This is speculation, I don't know whether you were owned.