If you pre-order the game from a store other than Paradox Plaza you aren't necessarily eligible for any pre order bonuses. Sometimes we include bonus icons, wallpapers etc but these are only included if you order from www.paradoxplaza.com unless specifically stated on the Steam store page that they are included there as well.
We've found that many vendors claim to sell pre-order keys when in fact they sell normal keys. This is because they are not partners of ours and buy their keys from the grey market. We always recommend you purchase your games from us or Steam to ensure you get what you pay.