Gentlemen,
We have the flag of the 5th Alabama Infantry captured at Chancellorsville here at the Alabama Department of Archives and History. It is WD #222 returned to us by the War Department effective March 25, 1905. The website to which you referred is mine. I do not know what the NPS has but I would suggest that perhaps they need to do a little provenance research. By the way I am a former NPS historian as well so, I mean no disrespect.
Robert Bradley
Chief Curator