JS下拉框去掉重复值

控制器
public ActionResult SelectBrokerage()
        {
            var listBrokerage = (from tbBrokerage in mysql.FQ_Brokerage
                                 select new
                                 {
                                     tbBrokerage.HandleID,
                                     tbBrokerage.HandleName,
                                 }).ToList();
            return Json(listBrokerage, JsonRequestBehavior.AllowGet);
        }

HTML
<select class="IncomeAreaSelect" id="HandleID">
   <option value="0">---请选择---</option>
</select>

JS:
$.get('/Huitubeccount/Expenses/SelectBrokerage', function (data) {//获取控制器方法名称
    $("#HandleID").empty();//去重复
    console.log(data);//输出
    $.each(data, function (a) {//遍历
        var str = ' <option value="' + data[a].HandleID + '">' + data[a].HandleName + '</option>'
        $("#HandleID").append(str);
    })
})

$("#HandleID").empty();//遍历前加上这行去掉重复值的代码

效果前

效果后