The coin check is a pretty weak authentication. For one, you are supposed to have also served in the unit. It isn't like anyone and everyone can go around asking for a coin check. Secondarily, I know a lot of people who don't carry their coins around with them. Them not having it is far from conclusive. For that matter, so is them having it...many units hand out coins as a form of thank you to other people. I've seen entire collections for sale.
A buddy of mine has several
He has them all framed & is most proud of the personal coin he was awarded by his former Command Sergeant Major