Option Explicit
Sub Ligne_insérer()
Application.ScreenUpdating = False
Dim i As Long
For i = Range("a65536").End(xlUp).Row To 3 Step -1 'adapter à la colonne
If Range("a" & i) <> Range("a" & i - 1) Then Range("a" & i).EntireRow.Insert
Next
Application.ScreenUpdating = False
End Sub