Second form item_check event problem.

Hello all,
I have two forms.On first form i am listing rooms and second form is for editing room. I am passing Room object from first form to second form. But before second form unload the secondForm Checkboxlist itemcheck event occurs.

I used boolean var with if statement for solving it but i have two checkboxlist, it was occured again at the second checkboxlist.
How can i stop it?
Thanks.