The coin dated 1959 has a normal obverse (no damage that I can see), an extremely faint reverse (compare the same type of 1961), is very slightly bowed, but the weight (to within .05 gram), diameter and as far as I can tell the thickness is the same as the 1961 dated coin). the 1959 dated coin also has quite a lot of rim nicks.
So is this just PMD as I suspect, or is it an error I cannot recognize? If PMD I would assume some kind of vise work, but I just want to be sure before tossing it.
Post mint damage. You cannot possibly have a full rim on one side, and no rim on opposite side. Striking a rimmed planchet and the collar die would make that impossible. Looks like it was ground down on a whetstone... only the devices are removed, so I would not expect it to have lost much weight.
"Research is what I am doing, when I don't know what I am doing" --Wernher von Braun