I have to say that I'm disappointed in the responses to Brian's question. Yes, many Hamilton ticket offers are scams, but not all are, and not one response has addressed that possibility. His scenario is a legitimate one - I know many people in other countries who have bought Hamilton tickets, and if they couldn't go, they would ask the same question. In the event that this is for real, Brian, I have a few ideas for you:
1. Have a friend in the U.S. handle the transaction for you.
2. If you have any friends in New York, it is almost 100% guaranteed that they know people who are dying to buy Hamilton tickets.
3. Ticketmaster may allow a ticket transfer (they do for some events, but I don't know if they do for Hamilton). With a ticket transfer through Ticketmaster, they void your tickets and reissue them to someone else so there's no risk of duplicate tickets. If no one on this board is interested, you can try selling them online on Craigslist, although since many ticket offers on Craigslist are scams, buyers are likely to be wary.
4. Call Ticketmaster and ask if the tickets can be returned and refunded.
5. See if an Escrow service like Escrow.com can be used to guarantee the transaction.
There are probably hundreds of thousands of people who would be willing to buy those seats at face value if they're legitimate. You should have no trouble selling them. You might even turn a profit. If they are not legitimate, then bless your heart.
Good luck to you.