From the update 62 video, it seems collector content and game key itself are not linked, will make things easier for a trade !
Since the key are separated, it means colelctor or not is not important for the trade of the game key itself. It also seems the second key doesn't benefit any collector bonus at all. As i've found someone to trade a collector key, the second key must be traded to a non collector as it doesn't have the collector stuff anyway.
My second key is still available to trade, if there's a kick starter backer that plan to go on steam anyway, you can make someone happy and play your game as intended !
If someone wish to exchange my second key for a gog one, i will hand out a key for a divity game (i already have them all !)
hope it'll encourage someone for the trade

Regards.
(Video :
http://youtu.be/sGngb4egREM )