Use the following code:
Public Sub New()
InitializeComponent()
RadSchedulerReminder1.TimeInterval = 500
Dim appointment As New Appointment(DateTime.Now.AddDays(-1), TimeSpan.FromHours(1), "A")
appointment.Reminder = New TimeSpan(10000)
Me.RadScheduler1.Appointments.Add(appointment)
Dim appointment2 As New Appointment(DateTime.Now.AddHours(-2), TimeSpan.FromHours(1), "B")
appointment2.Reminder = New TimeSpan(10000)
Me.RadScheduler1.Appointments.Add(appointment2)
RadSchedulerReminder1.StartReminderInterval = Date.Now.AddDays(-1)
RadSchedulerReminder1.EndReminderInterval = Date.Now.AddDays(1)
End Sub
Private Sub RadForm1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
RadSchedulerReminder1.StartReminder()
RadScheduler1.ActiveViewType = SchedulerViewType.Week
End Sub
Drag "A" on the same interval as "B". You will notice that the reminder dialog will continue to show only "B".