Fixes: #U4-1819

src/Umbraco.Tests/EnumerableExtensionsTests.cs

@@ -29,6 +29,10 @@ namespace Umbraco.Tests
 	                                                        new TestItem()
 	                                                            {
 	                                                                Children = new List<TestItem>()
+	                                                                    {
+	                                                                        new TestItem(),
+                                                                            new TestItem()
+	                                                                    }
 	                                                            }
 	                                                    }
 	                                            }
@@ -65,11 +69,15 @@ namespace Umbraco.Tests
 
 	        var flattened = hierarchy.Children.FlattenList(x => x.Children);
 
-            Assert.AreEqual(8, flattened);
+            Assert.AreEqual(10, flattened.Count());
 	    }
 
         private class TestItem
         {
+            public TestItem()
+            {
+                Children = Enumerable.Empty<TestItem>();
+            }
             public IEnumerable<TestItem> Children { get; set; } 
         }
 

src/Umbraco.Web/Mvc/AreaRegistrationExtensions.cs

@@ -7,7 +7,7 @@ using Umbraco.Core.Configuration;
 
 namespace Umbraco.Web.Mvc
 {
-	internal static class AreaRegistrationExtensions
+    internal static class AreaRegistrationExtensions
 	{
 	    /// <summary>
 	    /// Creates a custom individual route for the specified controller plugin. Individual routes

src/Umbraco.Web/Mvc/NotChildAction.cs

@@ -0,0 +1,20 @@
+using System.Web.Mvc;
+
+namespace Umbraco.Web.Mvc
+{
+    /// <summary>
+    /// Used to ensure that actions with duplicate names that are not child actions don't get executed when 
+    /// we are Posting and not redirecting.
+    /// </summary>
+    /// <remarks>
+    /// See issue: http://issues.umbraco.org/issue/U4-1819
+    /// </remarks>
+    public class NotChildAction : ActionMethodSelectorAttribute
+    {
+        public override bool IsValidForRequest(ControllerContext controllerContext, System.Reflection.MethodInfo methodInfo)
+        {
+            var isChildAction = controllerContext.IsChildAction;
+            return !isChildAction;
+        }
+    }
+}

src/Umbraco.Web/Umbraco.Web.csproj

@@ -322,6 +322,7 @@
     <Compile Include="Dictionary\UmbracoCultureDictionaryFactory.cs" />
     <Compile Include="Mvc\MemberAuthorizeAttribute.cs" />
     <Compile Include="Mvc\ControllerFactoryExtensions.cs" />
+    <Compile Include="Mvc\NotChildAction.cs" />
     <Compile Include="Mvc\SurfaceRouteHandler.cs" />
     <Compile Include="Search\ExamineIndexerModel.cs" />
     <Compile Include="Search\LuceneIndexerExtensions.cs" />