Fadec would make 2 engines harmonize easily.
But even without modern things like that, he venerable Sikorsky CH-37 Mojave proved that a 2-engine piston helicopter is fully workable. The Mojave had 2x Pratt and Whitney Wasp engines hanging in pods outside the main fuselage - driving the main blades through a shaft entering the fuselage and into the gearbox from each side.