原因是在同一时间有两条数据，处理方式在tooltip的formatter把数据放到set数组进行去重。

    tooltip: {
      trigger: 'axis',
      formatter: function (params) {
        const a = [];
        const b =[];
        const c =[];
        var res = "<div><p>"  + params[0].value[0] +"</p></div>";
        for (var i = 0; i < params.length; i++) {
          if (params[i].data != undefined) {
             a.push(params[i].marker);
             b.push(params[i].seriesName);
             c.push(params[i].value[1]);
          }
        }
        const seriesMakerList = [...new Set(a)];
        const seriesNameList = [...new Set(b)];
        const seriesValueList = [...new Set(c)];
        for (let i = 0; i <3 ; i++) {
          res += "<p>" +seriesMakerList[i]+ seriesNameList[i] + ":" + seriesValueList[i] + "</p>";
        }
        return res;
      }
    },