But, yeah where are the other three reverses? If those coins were struck two at a time, there would be un struck obverses. The Error is possible but we you would think one of the reverses would have shown up already.
But this begs the question What is full weight? The weight tolerance on the the two cents you posted was almost +/- .5 grams So I think it could be very believable for a heavy weight coin to have been ground down and still be at the full spec weight of 10.88 grams. (and a cent altered like that that was still the full 10.88 grams would be much more likely to have survived over the years as a "mint error" than an underweight example.)