I have gone to National Cemetaries for a while now, but I have NEVER seen tombstones indicating multiple fallen soldiers to the same stone. Taken at the National Cemetary in Fort Smith, AR, here from left to right, the tombstones indicate 20, 6, 5 and 10 Unknown Confederate Soldiers.
HDR image of 5 bracketed RAW shots with 0.7 exposure compensation per image. Taken with Nikon D300 and Nikkor 18-70mm lens. Post-processed using Photomatix Pro.