The stamp's probably as old as the coin. This crude style is known as American Primitive for obvious reasons. It's surely a merchant stamp...most likely a metalsmith of some sort. I see a lot of this type but unfortunately most are unidentified. A great piece and thanks for showing it. Bruce
No info, but must have stamped pretty hard, it certainly is a struck through. Other than that, it appears to be a nice 1807. You made a good choice.
Most counterstamped coins show some damage on the opposite side from the strike. Exceptions are the old British cartwheel pennies and two pennies...very large, heavy coins. They can handle a hard strike very well. Bruce
I've got a few old coins like this with counter stamps and always thought them pretty cool...there is a reference or two out there on the 'net with lists of the most common "stamps" with possible affiliated stampers.
I'd like to see your Counterstamped coins if you have images to share. Maybe I could help you with an ID. Most of the references...only a few...are way out of date but still useful. Greg Brunk published the last references I know of but the most up to date one is from 2013 and only includes US and Canadian issues. Bruce