Find duplicate values in column K then compare cells range of dups

[jonnybrovo815]

I have this code to identify differences of cells within specified rows:

Sub Macro2()
Dim rng As Range, cell As Range
Range("9:9,12:12").Interior.ColorIndex = xlNone
Set rng = Range(Cells(9, 1), Cells(9, Columns.Count).End(xlToLeft))
For Each cell In rng
If cell <> cell.Offset(3, 0) Then
cell.Interior.ColorIndex = 3
cell.Offset(3, 0).Interior.ColorIndex = 3
End If
Next

End Sub

However I would like to add to this a routine to find duplicate values in
column K and then run the above code to highlight the differences between the
cells in each duplicate row.

Can this be done?