Isso deve funcionar
Sub Chris()
Dim lrow As Long
With ActiveSheet
lrow = .Cells(65536, 1).End(xlUp).Row
.Cells(1).CurrentRegion.Sort key1:=.Cells(1), Header:=xlYes
Do
If .Cells(lrow - 1, 1) = .Cells(lrow, 1) Then
.Cells(lrow - 1, 4) = .Cells(lrow - 1, 4) + .Cells(lrow, 4)
.Rows(lrow).Delete
End If
lrow = lrow - 1
Loop Until lrow < 2
End With
End Sub
adaptado de source