Dont open your packs duplicate protection is not working!!!!!! Nice job Blizz........
It worked for me. The patch isn't out on mobile yet so if you opened them on mobile then it wouldn't be working. Also, if you already have 2 copies of all common cards in a set, it doesn't mean you'll only get rares and better.
Just for refrence you can still get dupes of cards you own. The rarity distribution is the same so if you owned 100% of commons but only 20% of rares each pack would still usually contain 4 commons. Maybe you know that already but I didn't understand how it worked when I first read the notes.
Meanwhile I didn't get my free deck dispite not playing since mid-october
Duplicate protection is working guys calm down. If you have all common cards and the pack you just opened has a common card it still can be duplicate. It does not give you a rare card instead of a common card in this situation.