1. A method of reducing show-through error in duplex printing comprising: performing a setup operation to determine at least one of sizes and locations of a first side image and a second side image of a duplex-printed image recording medium; determining an amount of residual magnification error based on the determined at least one of sizes and locations; determining margin shifts to reduce show through error due to residual magnification and registration error based on the determined amount of residual magnification error; and applying the determined margin shifts subsequently during printing of image data.