I know this is pretty much a necrobump, but you might want to check your facts.
This picture is from the Legacy Effects website (legacyefx.com) If you scroll down to "Maquettes - Collectibles" They post pictures of all the prototypes they have done. The Iron Man Mark VI Maquette being one of them.
As you can see from the original pics in question, it is the same color combination:
In addition, the following pic was taken at sdcc 2014:
Again, same color combination. As you can see from the above pic, it is next to the Sideshow Iron Man MK 42 and Iron Patriot. Kind of hard to "fake" those two when they haven't even been released yet.
I got this from an inside source who used to work for Sideshow. He / she stated that there were 3 prototypes made. One is still with Sideshow. According to the source, the prototype color scheme was modified for the regular released MK VI because the director of the Iron Man 2 movie made a last minute design change. Apparently he felt the MK VI prototype colors were too similar to the Iron Man 1 movie armor.