Well, It's bad.
You buy cookies, Register with email and input the code, You redeem it then you need to have the code saved or you can't log in again because you need to have the code to log in (Yeah, I made a mistake on not keeping the code or buying 4 bags to redeem all of them at once)
I bought 2 cookie bags, Input the code and redeemed them, Then in a few weeks I bought 2 more bags, I clicked already registered, I put in my email and code and guess what? Please enter a valid code, So I made a mistake to register again, I got the same codes
I click already registered again, Put in my email and my code and guess what, It says Please enter a valid code.
I hope that rare/microsoft won't do a promo like this, Please make it so we can login with our microsoft accounts on the site and claim it only once attached to our accounts.
This promo is bad and I'm not going to bother to get the rest of the codes to see if they work.