Games

Should be new, steam doesnt allow duplicate codes.

Just activate it and you will see.
If it is a new key, mark "received".
If it is a used key ask the giveaway creator for a un-used key.

I activated it worked but on my winning list, it says received. Anyway where does the giveaway creator get the codes?

I don´t get the point of this thread, you just activate your wins.

less than 1% of the GAs on this Page are "fake" or used keys:
https://www.steamgifts.com/stats/community/giveaways

Hello Aussie,im new too but for what i understand when you win a key here, you must activate it in your steam profile ,cant trade/sell it etc or you will get banned , if a key not work you can contact the giveaway creator for him give you another key,if the giveaway creator don't give it to you you can leave a negative feedback (sign key as not received) and also you can blacklist him if you want,if an user send more fake key more people then mark as not received and so then him is not able to create other giveaway or maybe get banned too.
Also is not possible to trade,sell or do whatever other thing with the key you win here,the only thing you can do is activate it in your profile,because if you don't do it then you will get banned.For know if a key work or not you must open the original valve store app called steam and rendeem the key code on it,if the code is valid you then can download the game,if cice versa the key is not valid steam will tell you that the code is already rendeemed (and you can also use button for recovery the account where the key is rendeemed).
you can read here rules of this community https://www.steamgifts.com/about/faq https://www.steamgifts.com/about/guidelines

Ohh and as you are kind of new:

Welcome to Steamgifts.
If you have not already done so, may I suggest you read the FAQ & guidelines. It is also a good idea to keep track of the announcements done by Steamgifts' admin.
In case you are unsure about the rules stated in the FAQ & guidelines, use the search function of the discussion board, as most questions have been asked plenty of time.
Enjoy your stay at Steamgifts & good luck!