A primary goal of military rifles is parts interchangeability. Your rifle went through an arsenal rebuild at some point and they replaced the barrel with one they pulled out of a pile of replacement barrels.
It affects the value as far as a collector's rifle goes since it is not original or "correct," but it makes no difference for a shooter and a rifle to enjoy. There are very few original or correct WWII rifles any more because the Army is interested in keeping rifles running, not in making sure the name on the barrel matches the name on the receiver. It is part of the rifle's history and you may still have the stampings on the stock to trace some of that history.
Keep shooting it until you need another barrel, and then you can look around for a SC barrel and make it correct again.