How to avoid creating duplicate appointments in MS Outlook using VB

Hello gurus,

I'm creating a plugin that creates appointments inside Outlook 2000+ from VB 6. I already have the code for creating those appointments, however, when I create an appointment with the same name and starting time as an existing appointment, Outlook creates a duplicate.  Is there any way to avoid duplicates?

Here's s a sample

Private Sub CommandButton1_Click()
    Dim objApp As Outlook.Application
    Dim objAppointment As Outlook.AppointmentItem
   
    Set objApp = New Outlook.Application
    Set objAppointment = objApp.CreateItem(ItemType:=olAppointmentItem)
   
   
        objAppointment.Subject = "Test"  'SUBJECT_MATTER
        objAppointment.Location = "Somewhere"
        objAppointment.Start = #1/13/2004 5:01:00 PM#
        objAppointment.Duration = 90
        objAppointment.ReminderMinutesBeforeStart = 15
        objAppointment.BusyStatus = olOutOfOffice
        objAppointment.Body = "blablabla"
        objAppointment.Sensitivity = olPrivate
       
        objAppointment.Save
End Sub

Thanks in Advance

JH