John Duff (counterfeiter) – Wikipedia John Duff, born John McElduff, or possibly John Michael McElduff, because early court records referred to him as John Michael Duff (September 1759 or August 1760 – June 4, 1799 or 1805), was a counterfeiter, criminal gang leader, horse thief, cattle thief, hog thief, salt maker, longhunter, scout, and soldier…