title: An item with the same key has already been added
body: <p>I get this error whenever I submit the form also the action method is not being called because of this:</p>
  
  <blockquote>
    <p>An item with the same key has already been added.</p>
  </blockquote>
  
  <p>And the exception details:</p>
  
  <blockquote>
    <p>[ArgumentException: An item with the
    same key has already been added.]<br>
    System.ThrowHelper.ThrowArgumentException(ExceptionResource
    resource) +52<br>
    System.Collections.Generic.Dictionary`2.Insert(TKey
    key, TValue value, Boolean add)
    +9382923    System.Linq.Enumerable.ToDictionary(IEnumerable`1
    source, Func`2 keySelector, Func`2
    elementSelector, IEqualityComparer`1
    comparer) +252<br>
    System.Linq.Enumerable.ToDictionary(IEnumerable`1
    source, Func`2 keySelector,
    IEqualityComparer`1 comparer) +91<br>
    System.Web.Mvc.ModelBindingContext.get_PropertyMetadata()
    +228    System.Web.Mvc.DefaultModelBinder.BindProperty(ControllerContext
    controllerContext, ModelBindingContext
    bindingContext, PropertyDescriptor
    propertyDescriptor) +392<br>
    System.Web.Mvc.DefaultModelBinder.BindProperties(ControllerContext
    controllerContext, ModelBindingContext
    bindingContext) +147<br>
    System.Web.Mvc.DefaultModelBinder.BindComplexElementalModel(ControllerContext
    controllerContext, ModelBindingContext
    bindingContext, Object model) +98<br>
    System.Web.Mvc.DefaultModelBinder.BindComplexModel(ControllerContext
    controllerContext, ModelBindingContext
    bindingContext) +2504<br>
    System.Web.Mvc.DefaultModelBinder.BindModel(ControllerContext
    controllerContext, ModelBindingContext
    bindingContext) +548<br>
    System.Web.Mvc.ControllerActionInvoker.GetParameterValue(ControllerContext
    controllerContext, ParameterDescriptor
    parameterDescriptor) +473<br>
    System.Web.Mvc.ControllerActionInvoker.GetParameterValues(ControllerContext
    controllerContext, ActionDescriptor
    actionDescriptor) +181<br>
    System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext
    controllerContext, String actionName)
    +830    System.Web.Mvc.Controller.ExecuteCore()
    +136    System.Web.Mvc.ControllerBase.Execute(RequestContext
    requestContext) +111<br>
    System.Web.Mvc.ControllerBase.System.Web.Mvc.IController.Execute(RequestContext
    requestContext) +39<br>
    System.Web.Mvc.&lt;>c__DisplayClass8.b__4()
    +65    System.Web.Mvc.Async.&lt;>c__DisplayClass1.b__0()
    +44    System.Web.Mvc.Async.&lt;>c__DisplayClass8`1.b__7(IAsyncResult
    _) +42    System.Web.Mvc.Async.WrappedAsyncResult`1.End()
    +141    System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult
    asyncResult, Object tag) +54<br>
    System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult
    asyncResult, Object tag) +40<br>
    System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult
    asyncResult) +52<br>
    System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult
    result) +38<br>
    System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
    +8836913    System.Web.HttpApplication.ExecuteStep(IExecutionStep
    step, Boolean&amp; completedSynchronously)
    +184</p>
  </blockquote>
  
  <h2>ViewPage</h2>
  
  <pre><code>&lt;%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/XYZ.Master"
      Inherits="System.Web.Mvc.ViewPage&lt;XYZ.Models.Admin.AdminSegmentCommissionsModel&gt;" %&gt;
      &lt;asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server"&gt;
          Create
      &lt;/asp:Content&gt;
      &lt;asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server"&gt;
          &lt;% using (Html.BeginForm()) {%&gt;    
              &lt;div class="box3"&gt;
                  &lt;div class="userinfo"&gt;
                      &lt;h3&gt;Admin Segment Commissions&lt;/h3&gt;
                  &lt;/div&gt;
                  &lt;div class="buttons-panel"&gt;
                      &lt;ul&gt;
                         &lt;li&gt;
                             &lt;input type="submit" value="Save" class="save" /&gt;
                         &lt;/li&gt;
                         &lt;li&gt;
                             &lt;%:Html.ActionLink("Cancel", "Index", new { controller = "AdminSegmentCommissions" }, new { @class = "cancel" })%&gt;
                             &lt;%--&lt;input type="button" value="Cancel" class="cancel" onclick="document.location.href='/AirlineLedgerTransactionReceiver/Index'" /&gt;--%&gt;
                         &lt;/li&gt;
                     &lt;/ul&gt;
                 &lt;/div&gt;
             &lt;/div&gt;
             &lt;div class="row-1"&gt;
                 &lt;div class="form-box1 round-corner"&gt;
                     &lt;div class="form-box1-row"&gt;
                         &lt;div class="form-box1-row-content float-left"&gt;
                             &lt;div&gt;
                                 &lt;label&gt;
                                     &lt;%: Html.LabelFor(model =&gt; model.FromSegmentNumber) %&gt;&lt;/label&gt;
                                     &lt;%: Html.TextBoxFor(model =&gt; model.FromSegmentNumber) %&gt;
                                     &lt;%: Html.ValidationMessageFor(model =&gt; model.FromSegmentNumber) %&gt;
                            &lt;/div&gt;
                        &lt;/div&gt;
                    &lt;/div&gt;
                &lt;/div&gt;
            &lt;/div&gt;
        &lt;%} %&gt;
  </code></pre>
  
  <p>
  
  
  
  </p>