If you really want to pay them money, order it again and return the old items. There is an option to not request money.

Companies are not allowed to charge for items they already shipped correctly or incorrectly. Even if they could, I can’t imagine it being easy for anyone to just bill you money and mark the order as completed without shipping anything.

From the FTC website - “By law, companies can’t send unordered merchandise to you, then demand payment. That means you never have to pay for things you get but didn’t order. You also don’t need to return unordered merchandise. You’re legally entitled to keep it as a free gift.”

Since they issued the refund, you got unordered items. It’s a business write off as a loss to the seller or Amazon.