Assuming for the moment that this is a genuine error, there are at least possibilities: (1) struck through "grease" on the obverse and an in-collar uniface strike on the reverse; (2) a low-pressure, in-collar uniface strike. The squared-off "rim" on the reverse face is incompatible with both scenarios. The lack of weakness in the interior of the obverse design, the relatively strong obverse design rim argue against scenario 2. The fact that the interior of the reverse face is flat as a pane of glass argues against both scenarios. The scratches on the reverse are likewise consistent with a coin that was altered outside the Mint. So, the totality of the evidence indicates that this coin was monkeyed with outside the Mint.
Error coin writer and researcher.