Removendo duplicidade no calendário Outlook

using System;
using System.Collections;
using System.Diagnostics;
using Microsoft.Office.Interop.Outlook;
namespace RemoveOutlookCalendarDuplicates
{
   class MainClass
   {
      [STAThread]
      static void Main(string[] args)
      {
         Application olApp = new ApplicationClass();
         NameSpace outlookNS =
            olApp.GetNamespace("MAPI");
         MAPIFolder calendarFolder =
            outlookNS.GetDefaultFolder(
            OlDefaultFolders.olFolderCalendar);
         while(true)
         {
            bool somethingDeleted = false;
            Hashtable uniqueItems = new Hashtable();
            foreach(AppointmentItem oi in calendarFolder.Items)
            {
               string uniqueKey =
               String.Format("{0} {1} {2:yyyyMMddhhmmss} {3:yyyyMMddhhmmss}",
               oi.Subject, oi.Location, oi.Start, oi.End);
               if(uniqueItems.ContainsKey(uniqueKey))
               {
                  Console.WriteLine("DELETED: " + uniqueKey);
                  oi.Delete();
                  somethingDeleted = true;
               }
               else
               {
                  uniqueItems.Add(uniqueKey, String.Empty);
               }
            }
            if(!somethingDeleted) break;
         }
         Console.WriteLine("** PRESS RETURN **");
         Console.ReadLine();
      }
   }
}