Item has already been added. Key in dictionary

Question

Item has already been added. Key in dictionary: 'Int32 Count[Object](System.Collecti:ons.Generic.IEnumerable`1[System.Object])'  Key being added: 'Int32 Count[Object](System.Collections.Generic.IEnumerable`1[System.Object])']

   System.Reflection.CerHashtable`2.Insert(K[] keys, V[] values, Int32& count, K key, V value) +7473762

Error Page:

Server Error in '/Admin' Application.

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Item has already been added. Key in dictionary: 'Int32 Count[Object](System.Collections.Generic.IEnumerable`1[System.Object])'  Key being added: 'Int32 Count[Object](System.Collections.Generic.IEnumerable`1[System.Object])'

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.ArgumentException: Item has already been added. Key in dictionary: 'Int32 Count[Object](System.Collections.Generic.IEnumerable`1[System.Object])'  Key being added: 'Int32 Count[Object](System.Collections.Generic.IEnumerable`1[System.Object])'

Source Error: 

Line 119:                     select q).ToList(); */
Line 120:
Line 121:        var Result = (idc.EventLocations.Join(idc.Cities, el => el.CityId, c => c.ID, (el, c) => new { el.id, StartDate = el.StartDate, el.RegClosingDate, el.EndDate, el.CountryId, el.EventId, el.CityId, CityName = c.Name }).Join(idc.Countries, eloc => eloc.CountryId, con => con.Id, (eloc, con) => new { eloc.id, eloc.CountryId, eloc.EventId, eloc.RegClosingDate, eloc.EndDate, eloc.StartDate, eloc.CityId, eloc.CityName, CountryName = con.Name })).Join(idc.Events, elocc => elocc.EventId, EvenId => EvenId.Id, (elocc, EvenId) => new { elocc.id, elocc.StartDate, elocc.EndDate, elocc.RegClosingDate, elocc.EventId, elocc.CityName, elocc.CountryName, EvenId.Picture }).Where(a => a.EventId == Convert.ToInt64(eventid)).OrderBy(b => b.RegClosingDate).ToList();
Line 122:
Line 123:        int cnt = Result.Count();

Source File: d:\IDCC\Website\IDCCircle\Admin\Events\EventDescription.aspx.cs    Line: 121 

Stack Trace: 

[ArgumentException: Item has already been added. Key in dictionary: 'Int32 Count[Object](System.Collections.Generic.IEnumerable`1[System.Object])'  Key being added: 'Int32 Count[Object](System.Collections.Generic.IEnumerable`1[System.Object])']
   System.Reflection.CerHashtable`2.Insert(K[] keys, V[] values, Int32& count, K key, V value) +7473762
   System.Reflection.CerHashtable`2.Preallocate(Int32 count) +301
   System.RuntimeTypeCache.GetGenericMethodInfo(RuntimeMethodHandle genericMethod) +240
   System.RuntimeType.GetMethodBase(RuntimeTypeHandle reflectedTypeHandle, RuntimeMethodHandle methodHandle) +438
   System.Reflection.RuntimeMethodInfo.MakeGenericMethod(Type[] methodInstantiation) +320
   System.Linq.Queryable.Join(IQueryable`1 outer, IEnumerable`1 inner, Expression`1 outerKeySelector, Expression`1 innerKeySelector, Expression`1 resultSelector) +301
   Events_EventDescription.bindLocations() in d:\IDCC\Website\IDCCircle\Admin\Events\EventDescription.aspx.cs:121
   Events_EventDescription.Page_Load(Object sender, EventArgs e) in d:\IDCC\Website\IDCCircle\Admin\Events\EventDescription.aspx.cs:53
   System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +14
   System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +35
   System.Web.UI.Control.OnLoad(EventArgs e) +99
   System.Web.UI.Control.LoadRecursive() +50
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +627

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Version Information: Microsoft .NET Framework Version:2.0.50727.5456; ASP.NET Version:2.0.50727.5456