Double Image. Two sets of designs on a struck piece, one superimposed on the other; or a portion of the total design doubled, or lettering only that is doubled. Such double images can be caused by any one of several malfunctions, as a shifting in the preparation of a hub, or a double punching (as of mintmarks) or a working die, or incorrect positioning of a final strike on a multiple-struck piece, or a broken tracer or cutting point during die cutting (on a pantograph); or by other causes. A close study of the die, or sometimes of the struck piece, and knowledge of coining and striking techniques are necessary to determine exactly what did happen to cause the doubling. Note how much is doubled and its location. For example, if the shifting is greater near the edge and less towards the center and the piece was coined it might be a double entry error of hubbing; the same evidence of a medal would imply it was incorrectly positioned for a final strike.