Button click event fired two times

Question

Hi,

I have an updatepanel. In this I have used modal popup for add some data. When i click on one link my modal popup will call. On modal popup ButtonOk is firied two time. Means once I have pressed that button and second time when I will refresh or press F5 to refresh the page, ButtonOk event will fire again. Will you please any one will give solution for this type of problem?

In my 6Months carrier I found first time this type of issue.