Part of the fun of Christmas is getting gifts from others. This gives my kids a chance to receive something that I would never have chosen for them. It would still be fun. I can't imagine screening gifts. If they opened something that bothered me I would explain honestly with the child why they couldn't have it. I try to choose honesty over deception. As for duplicates. Unless it is a game my kids love duplicate items. For example now they have twin dolls etc. If someone is thoughtful enough to spend their time choosing a gift then I will accept it.
I am blessed that all of our family is thoughtful and not too overboard with things. I will never buy the trendy toy of the year, so isn't it wonderful my girls have an aunt who loves to hunt down the "it" item of the season. Most of the time I don't even know what it is until the kids receive it.