Chart doesn’t automatically group dataPoints by its label. When only label is given (without x-value), internally it assigns x values to dataPoints in an order. So, there can be different dataPoints with same x value but different label. You can pass x-value along with label to group them accordingly. Please find the updated datapoints below.
data: [
{
type: "line",
dataPoints: [
{ x: 1, y: 30, label: "label1" },
{ x: 3, y: 40, label: "label3" },
{ x: 4, y: 50, label: "label4" },
{ x: 5, y: 60, label: "label5" },
{ x: 7, y: 90, label: "label7" },
{ x: 8, y: 20, label: "label8" },
{ x: 9, y: 50, label: "label9"}
]
}, {
type: "line",
dataPoints: [
{ x: 1, y: 10, label: "label1" },
{ x: 2, y: 20, label: "label2"},
{ x: 3, y: 30, label: "label3" },
{ x: 4, y: 40, label: "label4" },
{ x: 5, y: 50, label: "label5" },
{ x: 6, y: 60, label: "label6" },
{ x: 7, y: 70, label: "label7" },
{ x: 8, y: 80, label: "label8" },
{ x: 9, y: 90, label: "label9"}
]
}
]
Please take a look at this JSFiddle for complete code.