A system and method for adjusting a transport path length of a continuous web of recording media in a printing system printing duplex images. The method includes detecting alignment marks, for instance top of form (TOF) marks, on the continuous web of print media and adjusting the path length to provide substantially accurate registration of first and second images on opposite sides of the web for duplex imaging. The system to adjust path length includes idler rollers movable with respect to turnbar rollers.