I was looking recently at the NARA website for my father's POW records. They show Stalag12A to 9B. I know my father told me he was in Stalag 3A. I also found a record of someone he told me he was in camp with, also in 3A. Is it possible the NARA records are wrong?
While I wouldn't rule out the possibility of an error (I've seen them before in WWII records), it is also possible it is just incomplete. That is to say, it was not uncommon for POWs to have been in more than one POW camp. In a quick search, I found two instances of just that: Pvt. Frank Zito, Ex-POW Biography: Camps Held In: Stalag 3A, 12A and Stendal Have you tried to get your father's Official Military Personnel File (OMPF) from the NARA? That may contain more a more definitive answer.
Be sure to make it clear your request is from his "Next-of-kin". That may give your request a higher priority. If you are told by the NARA that his records were destroyed in the 1973 fire, don't lose hope. There may be another option you can look into.