Checking for form changes

[Gran Roguismo]

I am generating reports of a decent size and so it becomes important that I don't requiry the db every time I move onto a page, it would really slow down movement on the site.
So I have decided to take my form and put it into session as "oldReportForm" during the next call to the action I call it back out of the session, I compare and if anything has changed, I run my query.

 
SacReportForm rf = (SacReportForm) form;
SacReportForm oldRF = (SacReportForm) request.getSession().getAttribute("oldReportForm");
request.getSession().setAttribute("oldReportForm", rf);

the problem is this: Every time I compare oldReportForm has already been changed to match the current reportForm. I don't understand why though.
I am not doing request.getSession().setAttribute("oldReportForm", rf); anywhere else, and I take it out before I actually set it.

Also, if you have any suggestions for doing what I want in a better way, then they would be greatly appreciated.

[Merrill Higginson]

If you've changed the scope of the Form to "session" in the Struts config file, it is being kept in the session by Struts.

[Gran Roguismo]

currently the reportForm is being set to session in the struts config. The oldReportForm is not part of the config at all, so wouldn't be effected to my thinking.
I'm a little confused by your post though.