Questions about the role of copies in how we study the ancient Roman world have been asked for hundreds of years. Stretching from the ancient Roman ‘copies’ of Greek works which continue to be labelled in relation to no longer extant ‘originals’, to histories of plaster casts and their value as collected objects, and to more recent 3D printed examples and their machine-assisted material form. In contemporary display contexts such as museums, discussions continue about whether (modern) copies deserve floorspace and attention. In this paper I take this conversation back to ancient times and examine an episode from Roman history where a master maker was reportedly able to create a series of copies of a sacred shield that were so identical that no one could discern the difference. While the original aim was to create copies to protect the original, the result was a greater number of shields that needed to be kept safe and used in ritual. With this example I explore how copies can shift the parameters of authenticity in different ways and how an ancient tale of a perfect copy can contribute to contemporary museum debates.