code: function () {
  		var series = this,
  			chart = series.chart,
  			data = series.data,
  			closestPoints,
  			smallestInterval,
  			chartSmallestInterval = chart.smallestInterval,
  			interval,
  			i;
  
  		// sort the data points
  		stableSort(data, function (a, b) {
  			return (a.x - b.x);
  		});
  
  		// remove points with equal x values
  		// record the closest distance for calculation of column widths
  		/*for (i = data.length - 1; i >= 0; i--) {
  			if (data[i - 1]) {
  				if (data[i - 1].x == data[i].x)	{
  					data[i - 1].destroy();
  					data.splice(i - 1, 1); // remove the duplicate
  				}
  			}
  		}*/
  
  		// connect nulls
  		if (series.options.connectNulls) {
  			for (i = data.length - 1; i >= 0; i--) {
  				if (data[i].y === null && data[i - 1] && data[i + 1]) {
  					data.splice(i, 1);
  				}
  			}
  		}
  
  		// find the closes pair of points
  		for (i = data.length - 1; i >= 0; i--) {
  			if (data[i - 1]) {
  				interval = data[i].x - data[i - 1].x;
  				if (interval > 0 && (smallestInterval === UNDEFINED || interval < smallestInterval)) {
  					smallestInterval = interval;
  					closestPoints = i;
  				}
  			}
  		}
  
  		if (chartSmallestInterval === UNDEFINED || smallestInterval < chartSmallestInterval) {
  			chart.smallestInterval = smallestInterval;
  		}
  		series.closestPoints = closestPoints;
  	}
docs: Sort the data and remove duplicates