@nerviozzo96,

You can modify the content of toolTip using contentFormatter to display each dataPoints having the same x and y values in a single toolTip. Please check the below code snippet for customizing the content of toolTip –

toolTip: {
  contentFormatter: function(e){
    var content = "", dataPoint;
    for (var i = 0; i < e.chart.data.length; i++) {
      dataPoint = e.chart.data[i].dataPoints[e.entries[0].index];
      if(dataPoint && dataPoint.x === e.entries[0].dataPoint.x && dataPoint.y === e.entries[0].dataPoint.y){
        content += "<span style='color:" + e.chart.selectedColorSet[i] + "'>" + e.chart.data[i].name + "</span>: " + "<strong>" + dataPoint.y + "</strong>";
        content += "<br/>";
      }
    }
    return content;
  }
},

Also, kindly take a look at this JSFiddle for a working example.

___________
Indranil Deo
Team CanvasJS