Sub test()
On Error Resume Next
Sheets("PRONO_" & Format(Date, "dd-mm-yy")).Activate
If Err <> 0 Then
Worksheets("PRONO").Copy After:=Sheets(Worksheets.Count)
ActiveSheet.Name = ("PRONO_") & Format(Date, "dd-mm-yy")
Else
'L'instruction ci-dessous est facultative
MsgBox "Feuille ''" & ActiveSheet.Name & "'' déjà existante"
End If
On Error GoTo 0
End Sub