inserting two blank lines when based on data in a column

Try:

Sub ElConquistador()
Dim i As Long
For i = ActiveSheet.UsedRange.Rows.count To 2 Step -1
    If Range("A" & i).Value <> Range("A" & i).Offset(1).Value Then
        Range("A" & i).EntireRow.Offset(1).Resize(2).Insert xlDown
    End If
Next i
End Sub