How are two PCs ditinguished by the game if they are behind the same router?

[Haste]

The installer comes with some sort of spyware which records and sends the serial number of your hard drive away to the owners, admins or whoever.

I (used to) own a server in a different game. This game, to be precise. Guess what, it records that same number for, largely, banning purposes.

Not like ban evasion is unheard of, but yeah. Neither is this kind of anti-ban-evasion measure.

And yes, it's quite likely for both of you to have the same IP address. There often is no real way to know if it's two different people or one person multiclienting*, other than ingame behavior (one would assume it's quite difficult to fly two ships in combat at the same time as one person, for example).

*) The "One ship on the laptop, one on the desktop" type of multiclienting. Doing it on one system has become a bit harder recently.