How can I return a gift when it was a duplicate?

I received two of the same ebook as gifts from my wishlist — both emails came through at the same time. I’ve never had this happen before. When I googled it, it says there should be an option to exchange it for Amazon credit, but I don’t see this option in either email. I accepted one of the gifts before realizing the second was the same book. (They’re from different people.)

I would rather get another ebook I can read. I’m not sure who purchased the second one, so I’m not quite sure who to reach out to for a possible they refund/buy something else.