Posted By:
steve fUntil a new standard evolves (UV laser/ion/americium watermark?).. Sadly we'll never know.
I for one am guilty of cracking and resubmitting, quite often. My uneducated guess, about 50% of total prewar cards are counted twice. Only a small fraction of mine are sent for cross-grading, because SGC rarely upgrades PSA, BVG or GAI.