For i = 2 To Cells(Rows.Count, 3).End(xlUp).Row
If Range("C" & i).Value = "Duo" Then
If Range("G" & i).Value = Range("G" & i + 1).Value Then
Range("G" & i).Value = Replace(Range("G" & i).Value, Range("J" & i).Value, Range("I" & i).Value)
Range("G" & i).Value = Replace(Range("G" & i).Value, Range("J" & i + 1).Value, Range("I" & i + 1).Value)
Else
Range("G" & i).Value = Range("G" & i - 1).Value
End If
End If
Next