Could be the result of removing the copperplating. Inspect the coin for signs of copper on the edges or elsewhere. Some cents can get through the process with partial plating or missing plating, but an unplated cent lasting 34 years in the wild without dissolving would be an accomplishment...unless stored safely for most of the period before being put back into circulation.
Looks like the copper was removed. As for the doubling I agree with lDhair. MD Edit there also looks to be some tooling marks.
After the experiment to turn cents to silver, it was put in circulation and you now have the results? Just a thought.
Here's my Mantra - If it's dark, dull, and grey, it's been de-plated If it's bright and shiny, it's been re-plated The OP's coin has been de-plated
The weight is right, but difficult to be certain of the actual contributing factor for the missing copper. I figure that an authentic un-plated cent originates amongst of bag of cents of the same date/mm. Provenance might reasonably be established then. Amongst mixed cents (different dates/mms), the more likely contributor is a 'science experiment'...although remotely possible to be authentic. Age comes into play, since zinc deteriorates with moisture/exposure. Unless snagged very early before conditions like hydrozincite kick in, your coin would be rather ragged at this point. Unless, of course, it stayed hidden safe for 3+ decades before being returned to the wild. As most of us who CRH, you are going to come across these cents. Not with great regularity, but enough so that you start to understand that these cents are probably just 'science' experiments spent after getting the grade. Finding it in a driveway would not likely be attributed the same way a coin out of a roll could be though. So, I understand the need to put the question to the group. Quite reasonable. That added bit of information may explain some of the staining we see on your specimen. Exposure to the elements. I think that Fred's advice is pretty good though. If it's dull, it's likely a tampered coin where plating has been removed (but a remote possibility that its genuine). If it's shiny, it's almost certainly a plated coin. The original copper plating is a great flashing for a subsequent replating. Bu unless the provenance is established, authenticity will be problematic, I think.
