M1A1 stock buttplate number P237614 possible?

You heard a while nothing from me, but I'm still busy collecting carbines and I'm often asked the classic question (that you all know about): "Is this para stock original or not?" I'm busy in 2 WW2

 museums where I clean the carbines and over there almost all stocks are retrofit copies, often on Winchesters.....(because that's what people want obviously....not me...). Must be one of the 2 batches that Inland produced of course and in the right serial range. In my region (Eindhoven) where the 101st was active during Market Garden, so these stocks are highly sought after over here.

I'm so suspicious with these stocks that I almost trust none at all. I always use Carsons book to take a quick check.

This one that I saw last Sunday on a fair got me puzzled a bit. A lot checks out, but the serial number on the buttplate puzzles me. The fit of this stock is really good and tight (not this flimsy fake stuff). And it has got a RIA post-war rebuild marking. So its obviously not one the 101st used around Eindhoven.

From Carsons book I only see this number on it (many fakes have none at all) B257614

But this one has P237614.....

If you copy/fake something, why not this number then..........

Did one of you ever come across this P237614 number for a M1A1 stock? 

I'm a bit puzzled here.......

Here are some pictures as well, what do you all think. This is not my property but I'm researching for the seller that was on the fair.