Compare two ListBox selected Items and save the common selected to database in ASP.Net

Please refer this code

<div>
<asp:ListBox ID="ListBox1" runat="server" Height="150">
    <asp:ListItem Text="Apple" />
    <asp:ListItem Text="Banana" />
    <asp:ListItem Text="Orange" />
    <asp:ListItem Text="Watermelon" />
    <asp:ListItem Text="Strawberry" />
    <asp:ListItem Text="Pineapple" />
</asp:ListBox>
<br />
<asp:ListBox ID="ListBox2" runat="server" Height="150">
    <asp:ListItem Text="Apple" />
    <asp:ListItem Text="Banana" />
    <asp:ListItem Text="Watermelon" />
    <asp:ListItem Text="Pineapple" />
</asp:ListBox>
<br />
<asp:ListBox ID="ListBox3" runat="server"></asp:ListBox>
<br />
<asp:Button Text="Move Same to 3 Listbox" OnClick="MoveSame" runat="server" />
</div>

HTML

protected void MoveSame(object sender, EventArgs e)
{
    int listBox1Length = this.ListBox1.Items.Count;
    int listBox2Length = this.ListBox2.Items.Count;
    if (listBox1Length > listBox2Length)
    {
        this.SaveCommon(ListBox1, ListBox2);
    }
    if (listBox1Length < listBox2Length)
    {
        this.SaveCommon(ListBox2, ListBox1);

    }
    if (listBox1Length == listBox2Length)
    {
        this.SaveCommon(ListBox1, ListBox2);
    }
}

private void SaveCommon(ListBox lb1, ListBox lb2)
{
    foreach (ListItem item1 in lb2.Items)
    {
        foreach (ListItem item2 in lb2.Items)
        {
            if (item2.Text == item1.Text)
            {
                this.ListBox3.Items.Add(item2);
            }
        }
    }

}