Excel 2010, VBA Userform with ComboBox

I am able to populate ComboBox2 with the Filtered and visible data but, it also includes duplicates. How can I populate ComboBox2 with no duplicate data and only with the Visible data after its filtered.

Below is code that I am using:

'The Data has already been filtered and the combo displays the Filtered and visible data. I just need to remove the duplicates

Set rng = .Range("AllData").Columns(2).SpecialCells(xlCellTypeVisible)
For Each cel In rng

With Me.ComboBox2
.AddItem cel.Offset(0, 0).Value

End With


Any help is appreciated.
Regards