Bonus item code invalid.

[PsychicKoala]

Because you are trying to add a new account code onto an account you already have. You bought something you shouldn't have. You need to use the upgrade option. A 1.0 player was already given the game for free, they told you not to buy the game again about a month ago. But a zillion people must have missed this too because you're not the only person to do it. Wait to see if SE changes their policy of not allowing you to use a new account code onto an already made account, or try to get a refund and use the upgrade option.

[Patchy]

"You need to use the upgrade option."
-not paying another $20

"A 1.0 player was already given the game for free, they told you not to buy the game again about a month ago."
-The game is given for free, on launch day. I wanted early access, so I bought it. Don't care about the "free" part.

Whether or not I was 1.0 shouldn't matter, if I bought the CE, and I get a CE code, the code should register and see me as CE.

And, where did they say "don't buy the game"? I saw the "free part" but don't really care, but never saw anything about "don't buy it, because if you do, we'll take your money, your codes won't work and there is nothing you can do about it".