@yansonalvin97,
In the jsfiddle provided, a dataSeries is created for every unique ‘grade’. In that case, the first dataSeries has 4 dataPoints where as the remaining 5 dataSeries has 3 dataPoints each, for which the axisX labels are rendered accordingly. Also in any multiseries chart, the labels rendered along axisX will be that of the last dataSeries. Because of which you can see the label ‘2018-2019’ repeated. By disabling shared tootTip, you can observe this behavior clearly.
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Priyanka M S
Team CanvasJS