Asp.net-mvc – An item with the same key has already been added

I get this error whenever I submit the form also the action method is not being called because of this:

An item with the same key has already been added.

And the exception details:

[ArgumentException: An item with the
same key has already been added.]
System.ThrowHelper.ThrowArgumentException(ExceptionResource
resource) +52
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
System.Linq.Enumerable.ToDictionary(IEnumerable`1
source, Func`2 keySelector,
IEqualityComparer`1 comparer) +91
System.Web.Mvc.ModelBindingContext.get_PropertyMetadata()
+228 System.Web.Mvc.DefaultModelBinder.BindProperty(ControllerContext
controllerContext, ModelBindingContext
bindingContext, PropertyDescriptor
propertyDescriptor) +392
System.Web.Mvc.DefaultModelBinder.BindProperties(ControllerContext
controllerContext, ModelBindingContext
bindingContext) +147
System.Web.Mvc.DefaultModelBinder.BindComplexElementalModel(ControllerContext
controllerContext, ModelBindingContext
bindingContext, Object model) +98
System.Web.Mvc.DefaultModelBinder.BindComplexModel(ControllerContext
controllerContext, ModelBindingContext
bindingContext) +2504
System.Web.Mvc.DefaultModelBinder.BindModel(ControllerContext
controllerContext, ModelBindingContext
bindingContext) +548
System.Web.Mvc.ControllerActionInvoker.GetParameterValue(ControllerContext
controllerContext, ParameterDescriptor
parameterDescriptor) +473
System.Web.Mvc.ControllerActionInvoker.GetParameterValues(ControllerContext
controllerContext, ActionDescriptor
actionDescriptor) +181
System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext
controllerContext, String actionName)
+830 System.Web.Mvc.Controller.ExecuteCore()
+136 System.Web.Mvc.ControllerBase.Execute(RequestContext
requestContext) +111
System.Web.Mvc.ControllerBase.System.Web.Mvc.IController.Execute(RequestContext
requestContext) +39
System.Web.Mvc.<>c__DisplayClass8.b__4()
+65 System.Web.Mvc.Async.<>c__DisplayClass1.b__0()
+44 System.Web.Mvc.Async.<>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
System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult
asyncResult, Object tag) +40
System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult
asyncResult) +52
System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult
result) +38
System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
+8836913 System.Web.HttpApplication.ExecuteStep(IExecutionStep
step, Boolean& completedSynchronously)
+184

ViewPage

<%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/XYZ.Master"
    Inherits="System.Web.Mvc.ViewPage<XYZ.Models.Admin.AdminSegmentCommissionsModel>" %>
    <asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server">
        Create
    </asp:Content>
    <asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">
        <% using (Html.BeginForm()) {%>    
            <div class="box3">
                <div class="userinfo">
                    <h3>Admin Segment Commissions</h3>
                </div>
                <div class="buttons-panel">
                    <ul>
                       <li>
                           <input type="submit" value="Save" class="save" />
                       </li>
                       <li>
                           <%:Html.ActionLink("Cancel", "Index", new { controller = "AdminSegmentCommissions" }, new { @class = "cancel" })%>
                           <%--<input type="button" value="Cancel" class="cancel" onclick="document.location.href='/AirlineLedgerTransactionReceiver/Index'" />--%>
                       </li>
                   </ul>
               </div>
           </div>
           <div class="row-1">
               <div class="form-box1 round-corner">
                   <div class="form-box1-row">
                       <div class="form-box1-row-content float-left">
                           <div>
                               <label>
                                   <%: Html.LabelFor(model => model.FromSegmentNumber) %></label>
                                   <%: Html.TextBoxFor(model => model.FromSegmentNumber) %>
                                   <%: Html.ValidationMessageFor(model => model.FromSegmentNumber) %>
                          </div>
                      </div>
                  </div>
              </div>
          </div>
      <%} %>