When using the contract cards can you use the same card for 2 or 3 contracts if required. Eg. the Captain + Mdemoiselle and the Captain + Vice-roi. Or do you have to have 2 separate captain cards? No mention of this in the rules.
If you're talking about the expeditions you have to discard the cards in order to claim them so you can only use each card towards 1 expedition. The normal rules for cards is that all benefits stack but you can never pay less than 0 for a card. Hope that helps. FYI, rules questions are supposed to go in the game-specific forums. In this case https://boardgamegeek.com/boardgame/156009/port-royal/forums.... You might also find more useful clarifications there.