The Russian sniper was a real person but the famous duel with the German was a false story.
A guy who used to post on FR actually met the Russian Sniper in Moscow. Zaitsev? not sure of the spelling either admitted the story was not true or maybe just refused to confirm it. Anyway research after the war confirmed there was no Major Koenig who was supposed to be the German sniper.
Wow. I’ve read several stories on that. The German guy was supposedly the top sniper instructor.