Commented Issue: All MVC pages fail with the message "An item with the same key has already been added" [912]

Under some unknown conditions, all MVC pages fail with the message "An item with the same key as already been added". This issue has been reported on stackoverflow and forums.asp.net, see [All MVC pages fail with the message an item with the same key has already been added](http://stackoverflow.com/questions/15470118/all-mvc-pages-fail-with-the-message-an-item-with-the-same-key-has-already-been-a). I have had it happen 4 times in the past 6 months, and when this conditions happens, all MVC pages are unusable until an appPool reset. WebForm pages continue to operate without issue. This issue has spanned a migration to MVC3 to MVC4 and does not appear to be addressed in the latest nightly builds.

Comments: Woops, forgot to format the code... ``` System.ArgumentException: An item with the same key has already been added. at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add) at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector, IEqualityComparer`1 comparer) at System.Web.WebPages.Scope.WebConfigScopeDictionary.<>c__DisplayClass4.<.ctor>b__0() at System.Lazy`1.CreateValue() --- End of stack trace from previous location where exception was thrown --- at System.Lazy`1.get_Value() at System.Web.WebPages.Scope.WebConfigScopeDictionary.TryGetValue(Object key, Object& value) at System.Web.Mvc.ViewContext.ScopeGet[TValue](IDictionary`2 scope, String name, TValue defaultValue) at System.Web.Mvc.ViewContext.ScopeCache..ctor(IDictionary`2 scope) at System.Web.Mvc.ViewContext.ScopeCache.Get(IDictionary`2 scope, HttpContextBase httpContext) at System.Web.Mvc.ViewContext.SetClientValidationEnabled(Boolean enabled, IDictionary`2 scope, HttpContextBase httpContext) at ASP._Page_Views_Login_Index_cshtml.Execute() at System.Web.WebPages.WebPageBase.ExecutePageHierarchy() at System.Web.Mvc.WebViewPage.ExecutePageHierarchy() at System.Web.WebPages.StartPage.ExecutePageHierarchy() at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) at System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass1a.<InvokeActionResultWithFilters>b__17() at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation) at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation) at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult) at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass25.<BeginInvokeAction>b__22(IAsyncResult asyncResult) at System.Web.Mvc.Controller.<>c__DisplayClass1d.<BeginExecuteCore>b__18(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) at System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) at System.Web.Mvc.MvcHandler.<>c__DisplayClass8.<BeginProcessRequest>b__3(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) ```