We have been informed by godson's father that the book we sent from Amazon is a duplicate. I'm not sure if you can return it to Amazon but in similar circumstances I have said thank you very much and gone to stick it on ebay, regift, donate to charity etc. I wouldn't dream of saying we've already got it.
If we ask what he would like we are always told a cheque made out to parents so his mum can get something and we never find out what it was. He is not old enough to want vouchers to choose his own stuff.
AIBU to think if you are given a gift you accept politely as it is a gift willingly given and not an expectation?