> but issue different paper money while exchanging the old bills out of circulation While they're at it they could bring the notes into the 20th century by mak

> but issue different paper money while exchanging the old bills out of circulation While they're at it they could bring the notes into the 20th century by making them distinguishable from a distance and less easily damaged. If you need to distinguish the old notes from the new ones to prevent anyone getting scammed, might as well kill two or three birds with the one stone.