@papito,
When shared property of toolTip is set to true it lists all the dataPoints of corresponding x-value for each dataSeries. You can loop through the entries to get all dataPoints of corresponding x-value in contentFormatter as shown in the code snippet below –
function contentFormatter(e){
var content = " ";
for (var i = 0; i < e.entries.length; i++) {
var hashrate = e.entries[i].dataPoint.x;
if (hashrate < 1000000) {
content += (Math.round(hashrate / 1000) / 1000 ).toFixed(2)+' Sol/s';
content += "<br/>";
}
else {
var byteUnits = [ ' Sol/s', ' KSol/s', ' MSol/s', ' GSol/s', ' TSol/s', ' PSol/s' ];
var j = Math.floor((Math.log(hashrate/1000) / Math.log(1000)) - 1);
hashrate = (hashrate/1000) / Math.pow(1000, j + 1);
content += hashrate.toFixed(2) + byteUnits[j];
content += "<br/>";
}
}
return content;
}
Also, please take a look at this JSFiddle for a working sample.

___________
Indranil Deo
Team CanvasJS