diff --git a/test/Autofac.Specification.Test/Features/DecoratorTests.cs b/test/Autofac.Specification.Test/Features/DecoratorTests.cs
index e3174d235..7e337b234 100644
--- a/test/Autofac.Specification.Test/Features/DecoratorTests.cs
+++ b/test/Autofac.Specification.Test/Features/DecoratorTests.cs
@@ -281,6 +281,26 @@ public void DecoratorAppliedOnlyOnceToComponentWithExternalRegistrySource()
             Assert.IsType<ImplementorA>(service.Decorated);
         }
 
+        [Fact]
+        public void DecoratorCanBeAppliedTwiceIntentionallyWithExternalRegistrySource()
+        {
+            // #965: A nested lifetime scope that has a registration lambda
+            // causes the decorator to be applied twice - once for the container
+            // level, and once for the scope level.
+            var builder = new ContainerBuilder();
+            builder.RegisterType<ImplementorA>().As<IDecoratedService>();
+            builder.RegisterDecorator<DecoratorA, IDecoratedService>();
+            builder.RegisterDecorator<DecoratorA, IDecoratedService>();
+            var container = builder.Build();
+
+            var scope = container.BeginLifetimeScope(b => { });
+            var service = scope.Resolve<IDecoratedService>();
+
+            Assert.IsType<DecoratorA>(service);
+            Assert.IsType<DecoratorA>(service.Decorated);
+            Assert.IsType<ImplementorA>(service.Decorated.Decorated);
+        }
+
         [Fact]
         public void DecoratorCanBeAppliedTwice()
         {
diff --git a/test/Autofac.Test/Features/Decorators/OpenGenericDecoratorTests.cs b/test/Autofac.Test/Features/Decorators/OpenGenericDecoratorTests.cs
index 35dbe802f..7b9e2b537 100644
--- a/test/Autofac.Test/Features/Decorators/OpenGenericDecoratorTests.cs
+++ b/test/Autofac.Test/Features/Decorators/OpenGenericDecoratorTests.cs
@@ -550,6 +550,25 @@ public void DecoratorAppliedOnlyOnceToComponentWithExternalRegistrySource()
             Assert.IsType<ImplementorA<int>>(service.Decorated);
         }
 
+        [Fact]
+        public void DecoratorCanBeAppliedTwiceIntentionallyWithExternalRegistrySource()
+        {
+            // #965: A nested lifetime scope that has a registration lambda
+            // causes the decorator to be applied twice - once for the container
+            // level, and once for the scope level.
+            var builder = new ContainerBuilder();
+            builder.RegisterGeneric(typeof(ImplementorA<>)).As(typeof(IDecoratedService<>));
+            builder.RegisterGenericDecorator(typeof(DecoratorA<>), typeof(IDecoratedService<>));
+            builder.RegisterGenericDecorator(typeof(DecoratorA<>), typeof(IDecoratedService<>));
+            var container = builder.Build();
+
+            var scope = container.BeginLifetimeScope(b => { });
+            var service = scope.Resolve<IDecoratedService<int>>();
+            Assert.IsType<DecoratorA<int>>(service);
+            Assert.IsType<DecoratorA<int>>(service.Decorated);
+            Assert.IsType<ImplementorA<int>>(service.Decorated.Decorated);
+        }
+
         [Fact]
         public void DecoratorCanBeAppliedTwice()
         {