It's a close analogy, but it's not 100% accurate. The result is the same, sure, but it's for different reasons. Currency has exceedingly specific laws all to itself, whereas we're merely talking about simple trademark law.
Yes, of course the result is the same, apart from the prison sentence you get for counterfeit bills, and the length the police would go to trace the source.
The lesson to be learned is ... um, damn, your mate has lost his watch. Maybe he should have told her it was a rep or that he thought it could have been or something. It's a little late to play "I should have" though, as it'll just cause arguments and won't get his watch back.