From how the metal looks like as of now. Look at the 6th picture, leftmost gouge. The metal looks "pressed down", this is by a tool slicing it. Your nickel looks pitted around the holes because it is by corrosion, while this one is relatively even (although I see a hint of pitting/corrosion around the cut at "ABET"). If the holes were caused by corrosion, it would be more unevenly shaped and pitted around the hole's edges.