How to Prevent Events to Fire More Than Once

Public Class Form1
    Const curAmount As Double = 100
 
    Private Sub ComputeTotal()
        txtTotal.Text = curAmount * txtDays.Text
    End Sub
 
    Private Sub dtpFrom_ValueChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles dtpFrom.ValueChanged
        ComputeTotal()
    End Sub
 
    Private Sub dtpTo_ValueChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles dtpTo.ValueChanged
        ComputeTotal()
    End Sub
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim dtpStartDate As Date
 
        'Remove/comment the line below to simulate the error
        RemoveHandler dtpTo.ValueChanged, AddressOf dtpTo_ValueChanged
 
        dtpStartDate = dtpFrom.Value
 
        dtpTo.Value = System.DateTime.FromOADate(dtpStartDate.ToOADate + 1)
 
        AddHandler dtpTo.ValueChanged, AddressOf dtpTo_ValueChanged
 
        txtDays.Text = dtpTo.Value.Subtract(Format(dtpFrom.Value, "Short Date")).Days.ToString
 
        ComputeTotal()
    End Sub
End Class