Any type of paper stock produced—typically via lamination—with a different color on each side.
In screen printing, duplex paper is a type of paper used for the printing of decals in which a thin, water-absorbent tissue is laminated to a heavier stock. The decal design is commonly printed face down on the tissue side, and the decal is commonly affixed to its ultimate substrate by means of water or a varnish. Also known as duplex decal paper and double paper.