récupérer les doublons

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
Dim zone As Range, plage As Range, cel As Range
Set zone = [B:F] 'à adapter éventuellement
Set plage = Intersect(Target, zone)
If Not plage Is Nothing Then
  If plage.Rows.Count = 2 And plage.Columns.Count = zone.Columns.Count Then
    For Each cel In plage.Rows(2).Cells
      If Application.CountIf(plage.Rows(1), cel) Then UserForm1.ListBox1.AddItem cel
    Next
    UserForm1.Show
  End If
End If
End Sub

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
Dim zone As Range, plage As Range, d As Object, c As Range
Set zone = [B:F] 'à adapter éventuellement
Set plage = Intersect(Target, zone)
If Not plage Is Nothing Then
  If plage.Rows.Count = 2 And plage.Columns.Count = zone.Columns.Count Then
    Set d = CreateObject("Scripting.Dictionary")
    For Each c In plage.Rows(2).Cells
      If Application.CountIf(plage.Rows(1), c) Then d(c.Value) = c.Value
    Next
    UserForm1.ListBox1.List = d.keys
    UserForm1.Show
  End If
End If
End Sub