The two coins come from different reverse dies. The reverse of the PR67 has the rev of the 1922 high relief proofs. The rev of the 64 is the rev die of the 1921 high relief proofs which was not used on the 22 high relief proofs (matte or Satin) and until now the high relief 1922 obv and proof rev of 1921 has only been known on the unique 1922 high relief business stike. I strongly suspect the 64 is not a proof and is instead a business strike. (It is not close to being fully struck either. You would expect more from a proof. I suspect PCGS saw the high relief and just assumed "Proof".)
Other suspicions: At some point the coins were switched in their manilla envelopes because the "1 or 20" notation would fit the 67 coin since it has the dies on a 22 high relief proof and records indicate that 20 were struck. The statement on the other that the counter was 104,001 when this coin was pulled fits that of the high relief 1922 business strike run and the dies of the 64 coin fits that scenario.
Edited by Conder101
04/24/2014 09:29 am