checkboxlist weird behavior with attribute add onclick

[mlyons]

I have a web app with a checkboxlist. I set the text and value for
this checkboxlist at design time. I have a javascript function (that
does a confirmation box) added to this checkboxlist. The checkboxlist
has 2 items. If user clicks either check box, the app works fine.
However, if user clicks the text next to either of the check box items,
then I get the javascript confirmation twice.

Has anyone else encoutered this behavior? And does anyone have any
ideas (outside of changing them to individual check boxes) on why this
might be happening and a fix?

Thanks.