The problem of superposition of double broken line values of echarts

echarts uses to display two broken lines at the same time, why is there value accumulation?

 const option = {
                title: {
                    // text: ""
                },
                tooltip: {
                    trigger: "axis"
                },
                legend: {
                    data:["",""],
                    textStyle: {
                        color: "-sharpfff"
                    }
                },
                grid: {
                    left: "3%",
                    right: "4%",
                    bottom: "3%",
                    containLabel: true
                },
                toolbox: {
                    feature: {
                        saveAsImage: {}
                    }
                },
                xAxis: {
                    type: "category",
                    boundaryGap: false,
                    data: ["","","","","","",""],
                    axisLine: {
                        lineStyle: {
                            type: "solid",
                            color: "-sharpfff",//
                            width:"1"//
                        }
                    },
                    axisLabel: {
                        textStyle: {
                            color: "-sharpfff",//

                        }
                    }
                },
                yAxis: {
                    type: "value",
                    axisLine: {
                        lineStyle: {
                            type: "solid",
                            color: "-sharpfff",//
                            width:"1"//
                        }
                    },
                    axisLabel: {
                        textStyle: {
                            color: "-sharpfff",//

                        }
                    },
                    splitLine: {
                        show: true,
                        lineStyle:{
                            color:"-sharp3e4555",
                            type:"solid"
                        }
                    }

                },
                series: [
                    {
                        name:"",
                        type:"line",
                        stack: "",
                        data:[100, 132, 101, 134, 90, 230, 210],
                        itemStyle : {
                            normal : {
                                color:"-sharp03c4d5",
                                lineStyle:{
                                    color:"-sharp05b0c2"
                                }
                            }
                        }
                    },
                    {
                        name:"",
                        type:"line",
                        stack: "",
                        data:[100, 182, 191, 234, 290, 330, 310]
                    },

                ],

Nov.19,2021

remove the stack attribute in series so that
http://echarts.baidu.com/opti.

will not be superimposed.
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