How to stop processing of module pool screen after coming back from next screen?

Dear All,

I have two screens in dialog programming where the values of 1st screen is going to 2nd screen after some modification is done. I want to go back to 1st screen from 2nd one and get my modified values there. The problem is when I am using Back button of 2nd screen, the PBO and PAI of 1st screen again executes and processing the whole task. I don't want to process the whole task again. Is there any way to stop this at PBO of 1st screen ?

Thanks.

With regards.