gistfile1.txt

            // Uncomment the following three lines and we get exception, this gets fixed with scoped region
             var region = regionManager.Regions["ViewA"];
             region.Add(unityContainer.Resolve<ViewA>());
             region.Add(unityContainer.Resolve<ViewA>());

            // the following works
            // regionManager.AddToRegion("ViewA", unityContainer.Resolve<ViewA>());
            // regionManager.AddToRegion("ViewA", unityContainer.Resolve<ViewA>());