You may not have seen George Martin's reply to your question, which mentions Confederate dead buried at Groveton Cemetery near the battlefield of 2nd Manassas --
http://history-sites.com/cgi-bin/bbs53x/gacwmb/webbbs_config.pl?read=9197

Except for burials in few cemeteries such as Hollywood in Richmond VA, the vast majority of wartime Confederate dead are identified as only as "Unknown" or "CSA" or not marked at all.