selector dynamic add options always with one duplicate option

Question

var selector = document.getElementById("selectorId");
                          
                for (var i = 1; i <= 4; i++) {

                    selector.add(new Option(i, i));
                }

I add options dynamic using above code, and I expect 1,2,3,4 in the options, but there is always a duplicate option in the last:

Is this a bug?