The problem with Sawney's theory that this "mom and pop" internet
vendor is running a scam is this. UPS is not stupid. How many claims
for shipping damage do you think UPS will pay for one shipper before
they either refuse further shipments or call the cops for fraud?
Sure, a vendor could get away with it once in awhile, but it's kind of
hard to believe they could do it enough to make it worthwhile.

What to do is obvious. It's up to the shipper to pursue the claim with
UPS. Send them an email telling them that. And notify the credit card
company that you are disputing the unauthorized charge for the second
item, as well as a refund for the first legitimate transaction because
the item was returned.