How to remove unwanted sessions created in ssp

When I created my codes running under a Servlet, I noticed that there is only one session created - which is good. However, when I transferred some  of the methods to be executed under my ssp file, found that it created several session IDs. Is this normal?

 

I defined the maxInactiveInterval for the session to expire after 5 mins and I'm still using the default timeout value on the HTTPSession = 1200 (20 mins default expiration).

 

How can I remove unwanted sessions created when several methods were executed in my ssp? I am hoping to see only 1 session throughout the lifetime of my page. What should I do to remove these previous sessions created?

 

Hoping for your pieces of advice. Thanks!!!