Hi Tom,
From the master list found in the back of the late Richard Rollins' book, "The Damned Red Flags of the Rebellion," which covered the CS flags at Gettysburg comes these from the 12th New Jersey:
26th North Carolina Troops July 3, 1863 - WD 62 - location today - the MOC
47th North Carolina Troops July 3, 1863 - WD 86 - location today - the MOC
Those are the only two flags that I have the 12th New Jersey taking - or I should say the only two flags that Rollins has them taking. These flags are unmarked with unit designations so the ID confusion is not something unusual. I have seen units claim flags from Southern regiments that turned out to be wrong.
Hope this helps.
greg Biggs