Dom,

Thanks for the quick reply. Looks like this will work, but I have one further question. Where would I integrate this function? To be honest, I'm pretty green when it comes to VBA. I added the code from your link, and integrated the relevant parts to my macro, but I get the error "type mismatch". Here's what I have thus far.

 

Private Sub UserForm_Initialize()
    Dim a, i As Long, w()
    Dim NoDupes As New Collection
    Dim T As Integer, j As Integer
    Dim Swap1, Swap2, Item
    
    With Sheets("Holdings For Export")
    a = .Range("D4103", .Range("d" & Rows.Count).End(xlUp)).Resize(, 25).Value
    End With

    Set dic = CreateObject("Scripting.Dictionary")
    dic.CompareMode = 1
    For i = 2 To UBound(a, 1)
        If Not dic.exists(a(i, 1)) Then dic.Item(a(i, 1)) = Empty
        If IsEmpty(dic.Item(a(i, 1))) Then
            ReDim w(0)
        Else
            w = dic.Item(a(i, 1))
            ReDim Preserve w(UBound(w) + 1)
        End If
        w(UBound(w)) = a(i, 25)
        dic.Item(a(i, 1)) = w
    Next
        Dim AllCells As Range, Cell As Range
    
    
'   The items are in A1:A105
    Set AllCells = dic
    
'   The next statement ignores the error caused
'   by attempting to add a duplicate key to the collection.
'   The duplicate is not added - which is just what we want!
    On Error Resume Next
    For Each Cell In AllCells
        NoDupes.Add Cell.Value, CStr(Cell.Value)
'       Note: the 2nd argument (key) for the Add method must be a string
    Next Cell

'   Resume normal error handling
    On Error GoTo 0

'   Sort the collection (optional)
    For T = 1 To NoDupes.Count - 1
        For j = T + 1 To NoDupes.Count
            If NoDupes(T) > NoDupes(j) Then
                Swap1 = NoDupes(T)
                Swap2 = NoDupes(j)
                NoDupes.Add Swap1, before:=j
                NoDupes.Add Swap2, before:=T
                NoDupes.Remove T + 1
                NoDupes.Remove j + 1
            End If
        Next j
    Next T
    Me.ManagerSellEntity.list = dic.keys
End Sub