Hey Hips! I've been trying to win some of your auctions, you have great stuff! I am so hooked on R&R and all the ones I find to sell never seem to be ones that fit me, darnit!
I am a seller too and once or twice someone has accused me of selling fakes because the jeans they got don't look EXACTLY like a pair they already had. It's possible that (A) the pair they already have is fake or (B) its just a different style or from a different season and have some minor differences. I usually offer to show them a store receipt but let them return if they are not happy, its not worth a hassle, but I always maintain my items are real and tell them to get them authenticated if they wish...but yeah, it sounds like buyer's remorse to me. I'd wait to see if the jeans they send you back are real, and if they are the same ones, just refund and be done with it, but if they leave you a negative, reply to it that you have 100% proof of authenticity and for buyers to email you for proof. If they send you fakes, then get PayPal involved and do not refund. There's a Seller's Protection Policy too, dammit. I hate dealing with uninformed buyers like this.