Yes, I noticed that, too.
I really think so. As far as I know Sergio, Franco and Giancarlo were born in 1935, 1936 and 1938 respectively, and I remember reading in an old interview with Giancarlo that he worked on Totò a colori (1952) with his older brothers Bruno and Franco.
Other SWs in which Bruno is credited as master of arms are Days of Violence, The Great Silence, Sartana’s Here… Trade Your Pistol for a Coffin and Roy Colt and Winchester Jack.
Yes, that’s a good idea.