confirm executed multiple times, console.log only once in on('click') event

Question

I tried making a jquery function that works together with a bpopup (iframe) function. I want to show a confirmation message before trying to close the iframe. I added a confirm message that shows after a change but after i submit the form the confirm box gets duplicated. I tried debugging and checked how many times the function got executed so i did a console.log but this console.log only executed once when the confirm message got executed multiple times. this is the function:

function confirm_changed(){
    var changed = false;
    $('.b-modal', parent.document).on('click', function(){
        if(changed && confirm('Weet je zeker dat je dit scherm wilt verlaten?')){
            $('.b-modal', parent.document).removeClass('changed');
        }
    });
    $(document).one('input', function(){
        $('.b-modal', parent.document).addClass('changed');
        changed = true;
    });
}

This function gets called in the document.ready and this is the bpopup prototype function where i added the condition for the confirm message:

function r(){
    setTimeout(function(){
        if(c('.changed').length === 0){
            a.modal && c(".b-modal." + b.data("id")).fadeTo(a.speed, 0, function(){
                c(this).remove()
            });
            a.scrollBar || c("html").css("overflow", "auto");
            c(".b-modal." + e).unbind("click");
            f.unbind("keydown." + e);
            k.unbind("." + e).data("bPopup", 0 < k.data("bPopup") - 1 ? k.data("bPopup") - 1 : null);
            b.undelegate(".bClose, ." + a.closeClass, "click." + e, r).data("bPopup", null);
            clearTimeout(H);
            G();
            return !1
        }
    }, 0);
}

This function closes the iframe.

I added the timeout so that this function gets executed after the confirm message. after the form gets submitted and everything went through the validations the class gets deleted.