Similar here - no need to lie, but yes, always say thank you.

With gifts we don't like, or which are duplicates, we thank the giver and then when we get home, we chat with the boys about who might like the gift

Turn it around into something positive, and still we're able to be grateful that we received something, even if we're not wanting to keep it. And it gives a good opportunity to have a discussion about being thoughtful and intentional when we're picking gifts for others -- because it is the thought that counts, so we like to think and plan and be intentional