The edge has been altered. Much like a spooned coin, except instead of the entire edge being affected it is just one side and done on an angle. It appears thicker and deeper on that side because the edge has been flattened and somewhat folded over. The lettering following the inside curve of the area is absolute proof of post mint damage. How could a flat die strike in a curved arc? It could not, hence, it was struck normally first, then altered afterwards. Maybe only the person who did it could say how it was done, it is an odd one, but nothing in the minting process could account for it.