So I have a physical copy of Witcher Enhanced Edition, would it's product key work for redemption?

The thing is I bought a second copy on GOG not long ago and I don't intend to waste my product key on this account. I haven't used it since the 1.5 patch didn't require me to register my retail copy in the first place.

Yep... just redeemed my retail EE edition, bought a couple of years ago from Amazon.UK

So, I bought The Witcher Platinum Edition on physical media as well as a copy on Steam as well as a copy here on GOG. I suppose I'd rather redeem a copy of The Witcher 2 then... :p

Since I already have a bought copy on my account, what will happen if I try to activate my retail copy? Will I get an extra copy I can gift to someone?

I would think not. GoG gives you a possibility of a backup, this is not giving away free copies.

When will GOG plans to stop the process of backup of TW1 and TW2?

http://en.thewitcher.com/community/entry/258

Until June 30th it would seem.

It says "if they do not have their activation key". So if I have bought both games and they have activations codes I don't need to claim back-up copy until June 30th, right?

And something more. I have the Platinum Enhanced Edition of the Witcher. Does this veraion has an activation code? I can't find it anywhere

If they mean the TW/TW2 activation key, then yes. If they meant the GoG version activation key then no. It's very badly phrased, I'm confused by it. All retail versions should have their keys printed in the manual if I'm not mistaken.