I would have kept the second phone as a backup just in case anything went wrong with the first. Vodafone had you on file as only ordering one phone, the delivery report only had you down for one phone. All you signed for was one phone, if anyone did question you, the evidence says you accepted one phone. If it was the case that someone else was waiting for that second phone, they would have done exactly the same thing as you did and rang Vodafone to ask when they would be recieving their phone and Vodafone would process the order again for them. In my world, if someone makes a mistake, it's theur fault. If I make a mistake, fair enough, I made a mistake!