Duplicate bridge is a different game. It’s true that you can get by if you play exactly the same way as you would in a home social game or a team match. Duplicate pairs is a highly competitive game, though, and few contestants are happy just to ‘get by’. They want to win — not just once in a while but regularly!
To be successful at duplicate pairs, you must adjust your bidding. You must know when to compete vigorously, taking a risk in doing so. You must also know when it is right to bid conservatively. You have to understand which contract to choose in various situations. In the play and defense you meet similar dilemmas. Should you risk the contract for a lucrative overtrick? Should you risk giving away an extra trick in defense, hoping that you can beat the contract? This is a book that every novice bridge player needs to read before that first pairs game at their local club.
This is an excellent book on exactly what it says: Winning duplicate tactics (in the game of bridge). It is written for intermediates who want to learn how to adapt strategies for either match point games (usually pairs games) or IMPS (usually team games).