Macro To Create Duplicate Rows

try the following macro:

Sub Macro3()
'
Dim C_ell As Range
For Each C_ell In Range("C2", Cells(Rows.Count, 3).End(xlUp))
   If C_ell > 1 Then
    Rows(C_ell.Row + 1 & ":" & C_ell.Row + C_ell - 1).Select
    Selection.Insert Shift:=xlDown, CopyOrigin:=xlFormatFromLeftOrAbove
    Range(C_ell.Offset(0, -2), C_ell.Offset(0, 1)).Select
    Selection.Copy
    Range(C_ell.Offset(1, -2), C_ell.Offset(C_ell - 1, -2)).Select
    ActiveSheet.Paste
    C_ell.Resize(C_ell, 1).Select
    Selection = 1
   End If
Next
End Sub

If column D is not a formula, you can use this modified macro:

Sub Macro3()
'
Dim C_ell As Range, Qty As Integer
For Each C_ell In Range("C2", Cells(Rows.Count, 3).End(xlUp))
   If C_ell > 1 Then
    Rows(C_ell.Row + 1 & ":" & C_ell.Row + C_ell - 1).Select
    Selection.Insert Shift:=xlDown, CopyOrigin:=xlFormatFromLeftOrAbove
    Range(C_ell.Offset(0, -2), C_ell.Offset(0, 1)).Select
    Selection.Copy
    Range(C_ell.Offset(1, -2), C_ell.Offset(C_ell - 1, -2)).Select
    ActiveSheet.Paste
    C_ell.Resize(C_ell, 1).Select
    Qty = C_ell
    Selection = 1
    C_ell.Offset(0, 1).Resize(Qty, 1).Select
    Selection = C_ell.Offset(0, 1) / Qty
   End If
Next
End Sub