XL 2021 Identifier lignes des doublons dans message Box

Private Sub CommandButton1_Click()
Dim i As Long
Dim j As Long
Dim lastRow As Long
Dim doublons As String
Application.ScreenUpdating = False
lastRow = ActiveSheet.Range("B" & Rows.Count).End(xlUp).Row

For i = 5 To lastRow
For j = i + 1 To lastRow
If Cells(i, 2).Value = Cells(j, 2).Value Then
doublons = doublons & "Ligne " & i & " et ligne " & j & vbCrLf
End If
Next j
Next i

If Len(doublons) > 0 Then
MsgBox "Les lignes suivantes contiennent des doublons :" & vbCrLf & doublons
Else
MsgBox "Aucun doublon trouvé."
End If

Application.ScreenUpdating = True
End Sub