Highchart context menu button increments with page refresh - highcharts

Question

I have more than 1 highchart on a single webpage. However when I refresh the page I get another context menu button added to the additional highcharts. I have tried destroying the highchart before recreating to fix this but that didnt work. Any ideas how i can stop the context menu buttons from incrementing with page refreshes?
// Submits form values and ...
$('#dateform').submit(function (event) {
var data = $(this).serialize();
var monthSelect = $("#month option:selected").text();
var yearSelect = $("#year option:selected").text();
$("#reportDate").text(monthSelect + " " + yearSelect);
//-------------------------------------------------------------------------------
// Procedures - Bar
$.getJSON('reports_procedure_count_bar_ajax.cshtml', data, function (chartData) {
// Build the chart
$('#container1').highcharts({
chart: {
plotBackgroundColor: null,
plotBorderWidth: null,
plotShadow: false
},
title: {
text: 'Browser market shares at a specific website, 2014'
},
tooltip: {
pointFormat: '{series.name}: <b>{point.percentage:.1f}%</b>'
},
plotOptions: {
pie: {
allowPointSelect: true,
cursor: 'pointer',
dataLabels: {
enabled: false
},
showInLegend: true
}
},
series: [{
type: 'pie',
name: 'Browser share',
data: [
['Firefox', 45.0],
['IE', 26.8],
{
name: 'Chrome',
y: 12.8,
sliced: true,
selected: true
},
['Safari', 8.5],
['Opera', 6.2],
['Others', 0.7]
]
}]
});
});
$.getJSON('reports_procedure_count_bar_ajax.cshtml', data, function (chartData) {
// Build the chart
$('#container2').highcharts({
chart: {
plotBackgroundColor: null,
plotBorderWidth: null,
plotShadow: false
},
title: {
text: 'Browser market shares at a specific website, 2014'
},
tooltip: {
pointFormat: '{series.name}: <b>{point.percentage:.1f}%</b>'
},
plotOptions: {
pie: {
allowPointSelect: true,
cursor: 'pointer',
dataLabels: {
enabled: false
},
showInLegend: true
}
},
series: [{
type: 'pie',
name: 'Browser share',
data: [
['Firefox', 45.0],
['IE', 26.8],
{
name: 'Chrome',
y: 12.8,
sliced: true,
selected: true
},
['Safari', 8.5],
['Opera', 6.2],
['Others', 0.7]
]
}]
});
});
return false;
});