Now I am out of my element here. A dealer friend of mine showed me a lovely example of a Connecticut copper this morning. While that is interesting enough, here is the strange part. This particular coin was originally a Nova Constellatio. A large amount of the Nova's details are visible to the naked eye. Has anyone ever heard of such a thing? I have emailed http://www.eacs.org/ to see if that helps, but not heard back from anyone yet. If anyone has another idea please share.
If I understand you correctly you are saying the Conn. copper was struck over a Nova C. If this is the case - then yes I have heard of it. It is not unusal with overstrikes to be able to make out some of the details of the underlying coin. As to why you can see the details - it's only a guess on my part but I would say it is due to low striking pressure. For that time period overstrikes were quite common.
I have found a few on Coin Facts, but most appear to be on the New Jersey Coppers. 1888 seemed to be a good year for restriking coins. Now that someone else has heard of it I feel better. Thanks.
Here's an overstrike on a Nova C. Not exactly what you were asking about - but still an example. Nova C. overstrike
