Doesn't RA2 check serials over network?
I do remember having to install IPX to play over LAN.
The original release came with separate Allied/Soviet discs. You could put one in your buddy's computer.
Keygen was also easily available.
I don't think it did, or at least not the version I had, though it's entirely possible I am misremembering. I know for certain we did the same thing with StarCraft as well. Somehow, we got multiple instances of RA2 running on a LAN.
We’d start the game up in one computer, then pop the CD out and start it up in the next one, and so on.