Wallace, Chico and Nino are also twins, as well as Groggy and Pablo Ramirez(Even though Groggy is a gringo). The guys who keep getting shot and spinning around, played by Stefanelli, are also twins.Maybe Sergio just felt like using the same actors?
Com'on...Wallace,Chico and Nino...TWINS?? LOLICE
You are right, it and GBU would have made either must see sequils or barring that (since Eastwood left for the USA), just the further adventures of either Col. Mortimer, or Tuco would have been just great, how could that amazing opportunity have slipped away?
I'd rather see a prequel to GBU depicting the criminal adventures of Angel Eyes and Tuco.