Kramer's Pictures of Aparment residents

I dont' know if any one noticed this flaw. But in that episode where the K man takes pics and posts them on the lobby of the apartment, I recall that he used a Poloaroid instant pic. Later when Jerry's pic was defaced, Kramer said something like he will need to make duplicates to replace it ? Well, you can't make duplicates if your original was done from a Poloroid!