AITA… For keeping something wrongfully delivered to me

Basically, I ordered a laptop and when it was delivered, my fiancé signed for it and she was handed two boxes. She didn’t think much of it. I got home and realized that the second box was address to someone different, with their name and address. AITA if I keep the second laptop? Will fedex realize their mistake? Will fedex fix their mistake by paying the loss to the person who was expecting their laptop?