It's not stated specifically that a ship can only have one computer. If you want to give bonuses to more characters that is allowed by the restrictions on computers (no more than 4 bonuses, no more than 3 bonuses greater than 3 no more than 2 bonuses greater than 5).
Optionally there could be a limit of no more bonuses of +X or greater than you could get with one computer. So if you had a Mk 10 duonode you couldn't add any Mk. 6s or greater because that would mean more than 2 nodes of 6 or better, but you could add a Mk. 4 or
5 mononode or you could add two Mk. 3s or less.
