Script on scroll down javascript issue

I have a script in javascript that load more information on page scroll down. The problem is that when I scroll down the script is executed twice and I have the same result twice or even more.

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I want to execute the script once each time I scroll down and not execute it twice or even more each time.

This is the script:

$(window).scroll(function(){
                        
        var lastID = $('.load-more').attr('lastid');
        if ($(window).scrollTop() == $(document).height() - $(window).height() && lastID != 0){
            $.ajax({
                type:'POST',
                url:'getdata.php',
                data:'id='+lastID,
                beforeSend:function(html){
                    $('.load-more').show();
                },
                success:function(html){
                    $('.load-more').remove();
                    $('#list').append(html);
                }
            });
        }
    });