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

[Ponge]

Hello.

I recently read some sanctions (and the rules) about cheating, and one point got my attention:
Single player having more than one instance of Discovery open to fly their own characters is considered cheating (I presume this means running multiple instances of Discovery on the same computer).
I have shared characters with my brother, and we aid each other in getting some money (I fly the miner, he flies the transport, or vice versa, but on two different computers). As far as I know, this is not cheating, as two players are flying one ship each (despite we both have access to both characters).
I had a talk with one of my friends recently, and he said, both of our computers have the same IP on the Internet, as servers see the IP of the router.
My question is: how are two different computers distiguished by the Disco Server, if they are behind the same router (thus they have the same IP)?

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