ฉันต้องการไม่ให้สัญลักษณ์ marker symbol ซ้ำกัน มี code แนะนำฉันหรือไม่

marker: {
            symbol: "triangle"
        },

Highcharts.chart('container', {
            chart: {
               //????????? ??????? ??????????????? line ???????? 
              zoomType: 'xy',
             
            },
            title: {
              text: ""//????????
            },
           
    yAxis: {
              
        plotLines: [{
            color: '#FF0000',
            dashStyle: 'ShortDash',
            width: 2,
            value: 10,
        },{color: '#FF0000',
            dashStyle: 'ShortDash',
            width: 2,
            value: 20,
        },{color: '#FF0000',
            dashStyle: 'ShortDash',
            width: 2,
            value: 30,
            }],
        title: {
                    text: '}
            },
legend: {
    
          layout: 'vertical', //?????????????
          align: 'right', //???????
          verticalAlign: 'top',//???????????????????
          x: -0,    //???????????
          y: 30,  //??????????
         borderWidth: 0 //?????????
  },
  plotOptions: {
        series: {
            marker: {
                fillColor: '#FFFFFF', //??????
                lineWidth: 1,//?????????????????
                lineColor: null ,
                showInLegend: true,

            }
        }
    },

            series: [{