I once shipped a (1) N variety Millenium Beanie Baby to a lady who ordered the (2) NN Variety Millennium and she was irate. I let her keep the (1) N and shipped her a (2) N Variety.
I guess after ordering 1000's of things over the last 25 years (dvd's books, games and so on) from the USA 1 single time is extremely rare. And the seller may get the coin back if he does will buy it again. He has over 8000 feedback at 99.9% positive. So I know it is a honest mistake.