Visual Basic - Comparar el listado de un combobox

Public conta As Integer

Private Sub CommandButton2_Click()

MsgBox ("Se encontraron " & conta & " registros no duplicados, ver el combobox")

End Sub

Private Sub CommandButton3_Click()

Unload Me

End Sub

Private Sub UserForm_Initialize()

Dim sd As New Collection

Dim celda As Range

Dim dato

Dim r As String

Dim uf As Integer

Application.ScreenUpdating = False

On Error Resume Next

conta = 0

ComboBox1.Clear

Sheets("hoja2").Select

Range("A2").Select

uf = Range("A" & Rows.Count).End(xlUp).Row

r = "A2:A" & uf

For Each celda In Range(r)

sd.Add celda.Value, CStr(celda.Value)

Next celda

For Each dato In sd

ComboBox1.AddItem dato

conta = conta + 1

Next dato

Application.ScreenUpdating = True

End Sub