As we find out recently Online Key Store is sending out new sets of cd-keys for the game so that people who bought it from their store can easily re-activate their game once more on Steam.
Also G2Play is refunding (according to their response on Twitter):
So if you bought your key somewhere else and you’ve lost your game please do not hesitate and ask for a refund or a new key. And do not be afraid to use online key stores in the future – things like that happen but we cannot let Valve threat people with removing games and such.
Have fun playing!
Here’s a cool screenshot thanks to Rad86N: