Double Denomination Errors occur when a coin is properly struck by a coin press. The coin then is inadvertently placed into the hopper of another denomination and also struck by that coin press as well. An example is a copper planchet is struck by a set of Lincoln Cent dies but somehow get struck by a coin press with dime dies as well. The end result is both denominations show on a single coin. Post your comments and questions about Double Denominations in this forum area.