Paper board can be single of multiple. Paper board can be easily cut and formed, it is light weight and because it is strong it is used in packaging. Duplex board is a kind of paperboard or cardboard. It is called duplex board because it is made up of 2 layers. The exterior of the board is very often coated to make it more water resistant and to give it glossy sheen, but even uncoated duplex board is strong enough to make disposable cups.