 The duel between Zaitsev and Konig is fiction. There is, according  to modern research, no evidence that such a battle took place. There  was, though, a rumor amongst Russian soldiers about the story but no  witnesses or logs support it (probably it was just a rumor created  for increasing the will to fight amongst the Russian soldiers). The  German who was shot in the duel was SS sniper Colonel Heinz  Thorvald. The Germans claimed someone named Koenig had been shot in  the duel and not Thorvald because they didnt want to admit their  ace was down. This was claimed by Zaitsev, who also found the papers  on the body identifying him as Thorvald.