John Singleton Copley is the artist. Anyway the backgrounds are different. And I believe that the piece in Scotland is much smaller, so maybe a study for the version is LA? Or Maybe it goes the other way around. Many of you may be more familiar with JSC's portrait of Paul Revere. But we've all seen his work before.
I've no opinion on the pin or dirk puzzle.

Great piece of art thanks for sharing it with us.

Connaughton