I believe it is a hen pintail paint job, and the elongated tail kind of indicates it may have been carved as a hen pintail originally. Yeah it looks like that Mitchell/Joiner/Jobes/Chesapeake school of carving and paint. Who? You need someone who is more knowledgeable on Chesapeake Bay decoys than I to parse that out......
I believe it is a recent repaint based on your pictures and the overpainting of the speculums. Most of the Mitchells and other Ches. Bay decoys of that genre I handled seemed to have the speculums painted in one of the last things, on top of the wing detail.
I think you scored if you like it as a decoy. Heck you can't hardly get a wooden, ready to paint decoy for $20 anymore, let alone one that is painted in that characteristic Chesapeake style, even a repaint. So to my way of thinking, you got a good deal.
If it is a repaint and you want to make it look a bit older, you can age it with a coat (or more ) of Old English dent and scratch remover. It is a dark furniture polish and oil you can get at most super markets and household stores. Put a coat on, let it dry 10 minutes to 1/2 hour or so, then polish it and remover the excess. Let that rubbed out and polished coat dry 24 hours, and add another coat if you want it darker. While I'd never do this with an original paint decoy, or even one in old, in use repaint, I have done it to my own restoration paint jobs to add 50 years of age with excellent results.