Private Sub dgvFirmeBCode_CellValidating(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellValidatingEventArgs) Handles dgvFirmeBCode.CellValidating

If dgvFirmeBCode.Rows.Count > 0 Then
                For i As Integer = 0 To e.RowIndex - 2
                    If dgvFirmeBCode.Rows(i).Cells("TES1").Value = e.FormattedValue.ToString Then
                        duplicato = True
                        MsgBox("Articolo già inserito!")
                        e.Cancel = True
                        Exit For
                    Else
                        duplicato = False
                    End If
                Next
   End If
    
    End Sub