Some ANS 10 packs might have older ANS stickers in them?
I'm confused (not your fault, I was born that way)
yep. that's my understanding of 'buy back' cards from what I've read on the net.
usually the company (topps, upper deck, etc.) will do something special to the card - like get the baseball player to autograph the card and include a COA as proof, or simply put a foil stamp on it to show that it was packed in a newer set.
sometimes they don't do anything at all to the card, and there's no evidence that it's anything unique.
here's an old Superman 3 card that was put into the Topps American Pie set as a 'buyback'
I think the term indicates a company went out and 'bought back' old cards from dealers (or elsewhere) for use in a new set.
It could also really mean that topps had stacks of old ANS they need to get rid of, and instead of throwing them out, they are putting them into ANS10 packs and calling them something special.