I tried to show items without duplicate in List Box.
private void Lst_Box_SelectedIndexChanged(object sender, EventArgs e)
{
if (Chk_Multi.Checked == true)
{
Lst_Box.SelectionMode = SelectionMode.MultiSimple;
if (Lst_Box.SelectedItem == "Janvier")
{
Lst_Selected.Items.Add(Lst_Box.Text);
}
}
if (Chk_Multi.Checked == false)
{
Lst_Box.SelectionMode = SelectionMode.One;
Lst_Selected.Items.Add(Lst_Box.Text);
}
}