I bought a pair of these grips on ebay (got a singleton from Tom Heller). They were sold to me as Dutch grips, the ebay seller said they were P-08 grips from a parted out Dutch Luger. The one from Tom was virtually new; of the pair one shows evidence of having been on a gun for a while, the other seems newer.
None of the grips have markings inside, neither numbers nor a GS stamp. The ones I have are definitely P-08 grips, I wanted grip safety grips for my Dutch 06 Lugers and these are not relieved for a grip safety.
They are also different from what are commonly recognized as Dutch/Vickers grips. The usual Dutch grips are made of a dark, soft wood, crudely manufactured, larger than usual checkering diamonds, and the grips themselves are very thick in profile, extremely hand-filling.
These other grips are made of a lighter-shade, harder wood. They are quite well manufactured, the diamonds are much larger than even regular Dutch grips, very shallow-cut and flat. The grip panels are noteably thin in profile.
Here is a photo comparison, sorry the view is not better but its from photos which I have on file, not taken for the specific comparison. I think it will serve, however.
--Dwight