VBA Highlight Dupes in a Group

maybe

Sub colors()
Dim a, i As Long

a = Cells(1).CurrentRegion
For i = 2 To UBound(a, 1)
   If a(i, 1) & Chr(2) & a(i, 2) = a(i - 1, 1) & Chr(2) & a(i - 1, 2) Then
        Cells(i - 1, 1).Resize(2, 2).Interior.Color = vbYellow
    End If
Next i

End Sub