Well, I must step in here to prevent rather persistent misinformation from going any farther. There were never any plates prepared for the 1903 $50.
A model was not printed from plates. It was assembled from cut-out bits of engraving and sometimes included elements drawn by hand, all put together with glue.
Its purpose was to provide a design concept. The customer - the Finance Department in this case, but often a bank - would then decide whether or not to proceed to the engraving of plates. The Finance Department decided to drop the project and nothing more was done.