Index: Ringtoets/Common/src/Ringtoets.Common.Forms/TreeNodeInfos/RingtoetsContextMenuItemFactory.cs
===================================================================
diff -u -r3445838bcdcf9aa30bbc4b51f66be82812bd9b92 -ra71d7ff366aba9e2090ba8b8c0dbc32f5c815ad0
--- Ringtoets/Common/src/Ringtoets.Common.Forms/TreeNodeInfos/RingtoetsContextMenuItemFactory.cs	(.../RingtoetsContextMenuItemFactory.cs)	(revision 3445838bcdcf9aa30bbc4b51f66be82812bd9b92)
+++ Ringtoets/Common/src/Ringtoets.Common.Forms/TreeNodeInfos/RingtoetsContextMenuItemFactory.cs	(.../RingtoetsContextMenuItemFactory.cs)	(revision a71d7ff366aba9e2090ba8b8c0dbc32f5c815ad0)
@@ -223,7 +223,8 @@
                 Resources.CopyHS,
                 (o, args) =>
                 {
-                    IList<ICalculationBase> currentChildren = calculationContext.Parent.Children;
+                    CalculationGroup parent = calculationContext.Parent;
+                    IList<ICalculationBase> currentChildren = parent.Children;
                     int calculationIndex = currentChildren.IndexOf(calculation);
 
                     var copy = (TCalculation) calculation.Clone();
@@ -232,6 +233,7 @@
                                                            c => c.Name);
 
                     currentChildren.Insert(calculationIndex + 1, copy);
+                    parent.NotifyObservers();
                 });
         }
 
Index: Ringtoets/GrassCoverErosionInwards/src/Ringtoets.GrassCoverErosionInwards.Plugin/GrassCoverErosionInwardsPlugin.cs
===================================================================
diff -u -r8b60c9e846480f3ffeeb263bfea5d3367bf6bee3 -ra71d7ff366aba9e2090ba8b8c0dbc32f5c815ad0
--- Ringtoets/GrassCoverErosionInwards/src/Ringtoets.GrassCoverErosionInwards.Plugin/GrassCoverErosionInwardsPlugin.cs	(.../GrassCoverErosionInwardsPlugin.cs)	(revision 8b60c9e846480f3ffeeb263bfea5d3367bf6bee3)
+++ Ringtoets/GrassCoverErosionInwards/src/Ringtoets.GrassCoverErosionInwards.Plugin/GrassCoverErosionInwardsPlugin.cs	(.../GrassCoverErosionInwardsPlugin.cs)	(revision a71d7ff366aba9e2090ba8b8c0dbc32f5c815ad0)
@@ -875,6 +875,8 @@
 
             return builder.AddExportItem()
                           .AddSeparator()
+                          .AddDuplicateCalculationItem(calculation, context)
+                          .AddSeparator()
                           .AddRenameItem()
                           .AddCustomItem(updateDikeProfile)
                           .AddSeparator()
Index: Ringtoets/GrassCoverErosionInwards/test/Ringtoets.GrassCoverErosionInwards.Plugin.Test/TreeNodeInfos/GrassCoverErosionInwardsCalculationContextTreeNodeInfoTest.cs
===================================================================
diff -u -r8b60c9e846480f3ffeeb263bfea5d3367bf6bee3 -ra71d7ff366aba9e2090ba8b8c0dbc32f5c815ad0
--- Ringtoets/GrassCoverErosionInwards/test/Ringtoets.GrassCoverErosionInwards.Plugin.Test/TreeNodeInfos/GrassCoverErosionInwardsCalculationContextTreeNodeInfoTest.cs	(.../GrassCoverErosionInwardsCalculationContextTreeNodeInfoTest.cs)	(revision 8b60c9e846480f3ffeeb263bfea5d3367bf6bee3)
+++ Ringtoets/GrassCoverErosionInwards/test/Ringtoets.GrassCoverErosionInwards.Plugin.Test/TreeNodeInfos/GrassCoverErosionInwardsCalculationContextTreeNodeInfoTest.cs	(.../GrassCoverErosionInwardsCalculationContextTreeNodeInfoTest.cs)	(revision a71d7ff366aba9e2090ba8b8c0dbc32f5c815ad0)
@@ -56,10 +56,11 @@
     [TestFixture]
     public class GrassCoverErosionInwardsCalculationContextTreeNodeInfoTest : NUnitFormTest
     {
-        private const int contextMenuUpdateDikeProfileIndex = 3;
-        private const int contextMenuValidateIndex = 5;
-        private const int contextMenuCalculateIndex = 6;
-        private const int contextMenuClearIndex = 8;
+        private const int contextMenuDuplicateIndex = 2;
+        private const int contextMenuUpdateDikeProfileIndex = 5;
+        private const int contextMenuValidateIndex = 7;
+        private const int contextMenuCalculateIndex = 8;
+        private const int contextMenuClearIndex = 10;
         private readonly string testDataPath = TestHelper.GetTestDataPath(TestDataPath.Ringtoets.Common.IO, "HydraulicBoundaryDatabaseImporter");
 
         private MockRepository mocks;
@@ -172,6 +173,8 @@
             {
                 menuBuilder.Expect(mb => mb.AddExportItem()).Return(menuBuilder);
                 menuBuilder.Expect(mb => mb.AddSeparator()).Return(menuBuilder);
+                menuBuilder.Expect(mb => mb.AddCustomItem(null)).IgnoreArguments().Return(menuBuilder);
+                menuBuilder.Expect(mb => mb.AddSeparator()).Return(menuBuilder);
                 menuBuilder.Expect(mb => mb.AddRenameItem()).Return(menuBuilder);
                 menuBuilder.Expect(mb => mb.AddCustomItem(null)).IgnoreArguments().Return(menuBuilder);
                 menuBuilder.Expect(mb => mb.AddSeparator()).Return(menuBuilder);
@@ -234,8 +237,13 @@
                 using (ContextMenuStrip menu = info.ContextMenuStrip(nodeData, assessmentSection, treeViewControl))
                 {
                     // Assert
-                    Assert.AreEqual(15, menu.Items.Count);
+                    Assert.AreEqual(17, menu.Items.Count);
 
+                    TestHelper.AssertContextMenuStripContainsItem(menu, contextMenuDuplicateIndex,
+                                                                  "D&upliceren",
+                                                                  "Dupliceer deze berekening.",
+                                                                  RingtoetsCommonFormsResources.CopyHS);
+
                     TestHelper.AssertContextMenuStripContainsItem(menu, contextMenuUpdateDikeProfileIndex,
                                                                   "&Bijwerken dijkprofiel...",
                                                                   "Er moet een dijkprofiel geselecteerd zijn.",