Response.Cookies when sessionState mode="InProc"
===

I am wondering what the below code is doing? When sessionState  Mode is InProc or is it correct?
 - Response.Cookies(My.Settings.TESTSessionCookieName).Expires = DateTime.Now.AddYears(-1)
Why the previous developer used the above code instead of Sessioin timeout="20" to remove session.


Web.Config 

        ssionState mode="InProc" cookieName="TESTSession" timeout="20"

        <setting name="TESTSessionCookieName" serializeAs="String">
                <value>TESTSession</value>
        </setting>


Aspx.page.vb

        Session.Abandon()
        Response.Cookies(My.Settings.TESTSessionCookieName).Expires = DateTime.Now.AddYears(-1)
        Response.Redirect(My.Settings.generalErrorURL)

Any advice would be greatly appreciated.
Thank you/