This is called a novelty cent. The counterstamp is the state of New Hampshire (NH). These are made by private mints not the US Mint. Not an error. There is one for every state, Lincoln smoking a cigar and just about everything else imaginable. Do a google search for novelty Cents.
It clearly is not a mint error. I've pulled quite a few different counter stamped sate cents in my searches. I don't have a NH though.
It is an error If you consider that New Hampshire is upside-down. But seriously, there are 50 diferent states. And many-many more different ones. And Alaska.
Seriously, nothing like the one you posted? I told you, it's New Hampshire. It has a NH inside the outline of that state. If you can't see the numerous counterstamps available then all I can say is, exercise a little common sense will ya? No put down intended.
Interesting. I haven’t see these state counter stamped coins before. Time to start searching for other non-error coins.
The problem is you don't want to believe it so you do a cursory search and disregard anything you find. You are being extremely biased to wanting to find the mother load and disregarding Common sense in relation to how the Minting process works. Since these are HAND STAMPED each one may be slightly different. I googled this: novelty cent with state counterstamp Many similar items. https://www.google.com/search?q=novelty cent with state counterstamp&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjBxYe9ifbfAhWG5YMKHdTABKoQ_AUIDygC&biw=1277&bih=594
There are many people and companies doing things like this. The fact that you can't find an identical one is irrelevant. Any experienced collector (and a lot of inexperienced ones for that matter) know that this is a counterstamp. What would lead you to think it us an error? How would the mint accidentally stamp that design into the coin?
someone posted one of those just this week. https://www.cointalk.com/threads/stamp-on-penny-idenify.330726/#post-3304033.
I can probably rummage up a die stamp for you. Then you can stamp each and every coin you return to circulation with it. ... and give one cent to your brother. except some are really expensive .... because they are made of tool steel.