Buying double of everything is a big mistake. At its most basic, your twins' room will require a pair of cribs and a single diaper-changing station (because as you know, its impossible to change both babies at one time). Other essentials include a nursing chair and plenty of storage (because let's face it, you will acquire a lot of things with twins).
This issue of Fit Pregnancy showcases the nursery of Marcia Cross' twin daughters, Eden and Savannah which has plenty of pieces that will double in function and grow with the girls as they get older. These pieces include 2 Bratt Decor Dick Cribs, a Classic Bratt Decor Armoire with custom painted polka dots, a Dick dresser/changer and a play table for the girls' enjoyment.