Occasionally, some friends like to gift me things which is wonderful! The problem is they don't ask me if I have it or check if it was wishlist or not. This has lead to me receiving second or even third copy of an item I already own.

Items that are copy or copy/mod, mind you. I don't want to tell them I already own the gift as it sours the gesture and gift itself but on my end it is soured since I have to act surprised and grateful for something I already own.

I could ask the creators for a refund sure, but some don't reply and it is a hassle plus they lose out on lindens since SL takes a cut regardless. They can't go and click a "refund this item" button and save on fees.