Perhaps the intended use of the die at the time of its design and manufacture is what is relevant here, it was not designed to be used with the earlier reverse die, though it was, and presumably intentionally, in the penny in question. That does raise the question, which can never be answered I suspect, of how many of our 1860 and 1861 pennies are in fact mules, to go with the 1862 obv 2 and 3 coins which clearly are ‘intentional mules’?
Better not get into semantics or we may all end up asses.
Jerry