Populating ListBox with the selected Items from other LisBox.

 <asp:ListBox ID="ListBox1" SelectionMode="Multiple" runat="server">
<asp:ListItem>1</asp:ListItem>
<asp:ListItem>2</asp:ListItem>
<asp:ListItem>3</asp:ListItem>
</asp:ListBox>
<asp:ListBox ID="ListBox2"
SelectionMode="Multiple" runat="server">
</asp:ListBox>

<asp:Button ID="Button1" runat="server" Text="Button"
onclick="Button1_Click" />


 protected void Button1_Click(object sender, EventArgs e)
    {
        foreach (ListItem item in ListBox1.Items)
        {
            if (item.Selected == true)
            {
                ListBox2.Items.Add(item);
            }
        }
    }
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