I just put an A1 stock on my AR and switched the buttplate over from my A2 stock. I noticed the A2 plate is a little narrow for the A1 stock. It doesn't cover the edges of the stock. I bought the A1 stock from CDNN and it was advertised a a new Colt stock. The A2 stock was purchased from a guy here on the forum that was/is selling a bunch of A2 stocks and M16 furniture sets.

Is it normal for A1 stocks to be a little fatter than A1 stocks, or is this just an anomaly? Does someone sell A2 buttplates that are known to be a little fat so they will have a better fit on A1 stocks?

It's just an anomoly.  My preffered fixed stock used to be the A1 with an A2 buttplate (I still have one on my M16A4 clone).  I've never noticed a problem with the edges not meeting up.

I have two A1 stocks that I tried to mount the A2 buttplates onto, and I had the exact same problem you did.  My A1 stocks are military surplus and still have the spray painted stenciled rack numbers on 'em.  The buttplates I tried were Bushmaster and generic.

If it's an anomaly, I wonder if the problem is with the A2 or the A1.

No anomoly -- the contour of the A1 stock and the A2 buttplate DO NOT EXACTLY MATCH.  I have two A1 stocks and tried a variety of A2 buttplates from Bushmaster & Armalite.

OK. I guess I'll just have to live with it.

Colt A2 buttplate on Colt A1 stock.  Same situation; so it's not the maker  The one I have on mine isn't that much narrower, just a tad. Can't really see it so much as feel it when you run your finger around the edge.

I can live w/it