The Soviets got the Breda MG in the Stalingrad campaign. I believe the only reason they did was because I have seen some photos of Soviet soldiers with captured Bredas from Italians on the Eastern Front. Or also because the devs just wanted to throw in something random in for variety
Since with the major update theoretically you will have Italians fighting in Stalingrad, if you want a Breda as a Soviet go hunt it off an Italian yourself.