Nope.

Just off hand i'm going to say no...

However there are programs between steam and GoG where you can get the copy on other platforms when it qualifies certain criteria, like proving you have the game on one platform and then activating it on the other free of charge. However at no point are you given a code.

I can't imagine why on earth you would even think this.
Steam is Steam, and GOG is GOG. If you buy on Steam, you get it in your Steam library. If you buy it on GOG, you get a DRM-free copy in your GOG library. Simple as that.

<Laughs in GOG>

Of course you do. You will also getting a Nintendo WiiU copy to share with a friend.

Does that also include a Wii, GC and SNES copy just in case you have one of those systems?

Sadly no, but if you ask nicely you can get an MSX copy.

Hmmm and i was so looking forward to pulling my SNES out of the closet...

16-bit Witcher would be interesting.

As Jesse Cox would say: GoG! Get it done!

:)

Sometimes, GOG allow their users to get a free copy of a game they bought on Steam. You can do it here:
https://www.gog.com/connect

If you buy The Witcher 2 in Steam, you get a copy for GOG, for example.

Could be fun. I wonder how it could work out... Zelda style? Or turn-based fights?
If you wait another year, they might offer such a deal, but currently Witcher 3 is still fairly new.

Dare I say it would be a great point and click adventure.