title: Stacking Highcharts data in an xrange data series
body: <p>I am creating a gantt chart showing my advertising buys for the year. Everything is working well except when I have data on the same y axis. The data ends up displayed one on top of the other. How can you stack the data show both can be displayed. Here is a JSFIDDlE showing my dilemma. <a href="http://jsfiddle.net/tagriffith/a16mgm04/1/" rel="nofollow">http://jsfiddle.net/tagriffith/a16mgm04/1/</a></p>
  
  <p>When I want to show the radio spots in the same y (4) series and they have the same run dates the data gets stacked on top of each other. Below is the partial code from the jsfiddle.</p>
  
  <pre><code>[{
      name: 'Radio',
      groupPadding: 0,
      borderRadius: 0,
      pointWidth: 20,
      data: [{
          name: 'WLW',
          x: Date.UTC(2015, 12, 4),
          x2: Date.UTC(2015, 12, 20),
          y: 4
        }, {
          name: 'WNKU',
          x: Date.UTC(2015, 12, 4),
          x2: Date.UTC(2015, 12, 20),
          y: 4
        },
  
        {
          name: 'WGUC',
          x: Date.UTC(2015, 12, 4),
          x2: Date.UTC(2015, 12, 20),
          y: 4
        },]]
  </code></pre>