Chart.js multiTooltip labels

Change

window.myBar = new Chart(ctx).Line(barChartData, {
   responsive : true,
   animation: true,
   barValueSpacing : 5,
   barDatasetSpacing : 1,
   tooltipFillColor: "rgba(0,0,0,0.8)",                
   multiTooltipTemplate: "<%= label %> - <%= value %>"
});

to:

window.myBar = new Chart(ctx).Line(barChartData, {
   responsive : true,
   animation: true,
   barValueSpacing : 5,
   barDatasetSpacing : 1,
   tooltipFillColor: "rgba(0,0,0,0.8)",                
   multiTooltipTemplate: "<%= datasetLabel %> - <%= value %>"
});

The change is to the last line

multiTooltipTemplate: "<%= datasetLabel %> - <%= value %>"

datasetLabel gets the value of the label from the dataset objects (in this case ‘Bob’ and ‘Tina’), whereas label gets the caption printed on the x-axis (part of the labels array)