Mr. Bates, first let me apologize for taking so long to get back to you.I did do a few more lookups for you in the lesser known resources at NARA to see if I might find something to bolster your case.
As I understand it, the DAR was having a problem with "Mr. Duval" who picked up Reuben's pay (per Reuben's service record) as being the same Captain or Major Duval who had served along with him.
William Duval is a pensioner, so I looked for a "final pension payment" file for him at NARA.He did have one.The source citation for this record is:"NARA Record Group 217, entry #722, Virginia, box #7".William Duval was pensioned under the act of 1832. In this file, William gives his affidavit from Buckingham Co., VA, on 1 October 1841.He says his rank was Lieutenant and Captain.He says that he now resides in Buckingham Co., and has resided there for 34 years, and previous to that was in the city of Richmond.
This may be what DAR is hung up over.According to this, he never lived in Louisa County, HOWEVER, you are correct that his pension documents tell a different story.In his original declaration for pension he stated, "About 1781 I bought a farm called Pottis' Hills of a merchant of the name of George Pottis in the lower end of Louisa.In October 1783 I removed to my former seat near Richmond".
So if DAR is looking at what he said in his final payment file, they would say it is the wrong William Duval.But if they look at the documents in William Duval's pension file, they will see that it is the correct William Duval.
As to the confusion in the soldier's rank, he served in the Virginia Militia and also in the Continental Line, and had differing ranks.You are correct, however, that the fact that he was "Mr. Duval" does not mean that he couldn't have been the same Captain or Major Duval.
If you haven't already done this, my suggestion would be to look at some deeds for Louisa County and find George Pottis as the grantor, and William Duval as the grantee.Get a copy of that deed (available on microfilm at the Library of VA) and compare the signature of the William Duval on that document with the signature of the William Duval who picked up the paycheck.If they match, that would be tough for DAR to argue with.