title: Highcharts - multi line chart - line above line
body: <p>I have a chart with two lines that have the same values in some of the points. Which causes one line to be on top of the other while the other line "disappears"<br>
  Suggestions on how I can avoid that?<br>
  <a href="http://jsfiddle.net/t2jyfLds/1/" rel="nofollow">http://jsfiddle.net/t2jyfLds/1/</a>  </p>
  
  <pre><code>$(function () {
    $('#container').highcharts({
      title: {
          text: 'Monthly Average Temperature',
          x: -20 //center
      },
      subtitle: {
          text: 'Source: WorldClimate.com',
          x: -20
      },
      xAxis: {
          categories: ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun',
              'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec']
      },
      yAxis: {
          title: {
              text: 'Temperature (°C)'
          },
          plotLines: [{
              value: 0,
              width: 1,
              color: '#808080'
          }]
      },
      tooltip: {
          valueSuffix: '°C'
      },
      legend: {
          layout: 'vertical',
          align: 'right',
          verticalAlign: 'middle',
          borderWidth: 0
      },
      series: [{
          name: 'Tokyo',
          data: [7.0, 6.9, 9.5, 14.5, 17.0, 17.0, 17.0, 17.0, 17.0, 17.0, 7]
      }, {
          name: 'New York',
          data: [-0.2, 0.8, 5.7, 11.3, 17.0, 17.0, 17.0, 17.0, 17.0, 17.0, 10]
      }]
    });
  });
  </code></pre>