Option Explicit

Function UConcatVal(rng As Range) As Variant
Dim srr() As Variant, urr() As Variant, i As Long, ConcatVals() As Variant, UniqueVals As New Collection
srr = rng
On Error Resume Next
With UniqueVals
    For i = LBound(srr, 1) To UBound(srr, 1)
        .Add CStr(srr(i, 1)), CStr(srr(i, 1))
        If Err Then
            ConcatVals(.Count) = ConcatVals(.Count) & ", " & CStr(srr(i, 2))
        Else
            ReDim Preserve ConcatVals(.Count)
            ConcatVals(.Count) = CStr(srr(i, 2))
        End If
        Err = 0
    Next i
On Error GoTo 0
End With
ReDim urr(1 To UniqueVals.Count, 1 To 2)
For i = 1 To UniqueVals.Count
    urr(i, 1) = UniqueVals(i)
    urr(i, 2) = ConcatVals(i)
Next i
UConcatVal = urr
End Function