This multiple chart issue usually happens when you hover the mouse to a coordinate that already contains existing data that was just replaced by another data returned from an asynchronous request.

The Workaround

Suppose you have an instance of a pie chart for example:

new Chart(context).Pie(data);

Assign that instance to a variable and specify that variable as a property of the window object like so:

window.pieChart = new Chart(context).Pie(data);

Afterwards, add an if condition before it that checks if window.pieChart already exists and if so, remove it like so:

if (window.pieChart !== undefined) {
  window.pieChart.destroy();
}

window.pieChart = new Chart(context).Pie(data);