Techniques to prevent leakage of fluorescing signals through print media or indicia tape

A substrate structure encoded with information bearing indicia includes a substrate having a first surface and a second surface. Formed on the first surface is a first information bearing indicia defined by a fluorescent material. A second information bearing indicia is defined by a fluorescent material positioned adjacent to the second surface, the second indicia and the first indicia in an overlapping relationship. The substrate structure includes apparatus for preventing interference between the first indicia and the second indicia during a detection process. The interference preventing apparatus can include reflective or absorptive coatings formed on the first and second surfaces of the substrate, the first and second information bearing indicia positioned on the respective reflective coatings, a thin metal foil layer positioned between the first indicia and the second indicia, or a black background disposed between the first and second indicia.