title: Bootstrap table - Duplicate table header
body: <p>When I try to remake this example of Group Columns: <a href="http://issues.wenzhixin.net.cn/bootstrap-table/index.html#options/group-columns.html" rel="nofollow">http://issues.wenzhixin.net.cn/bootstrap-table/index.html#options/group-columns.html</a>
  from the Bootstrap table documentation, I get a wrong result. The header gets duplicated and shown twice.</p>
  
  <p>My code is here:
  
  
  <pre><code>TYPE html&gt;
  &lt;html&gt;
  &lt;head&gt;
      &lt;title&gt;Group Columns&lt;/title&gt;
      &lt;meta charset="utf-8"&gt;
      &lt;link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.2.0/css/bootstrap.min.css"&gt;
      &lt;link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-table/1.8.1/bootstrap-table.min.css"&gt;
      &lt;script src="https://code.jquery.com/jquery-1.11.0.min.js"&gt;&lt;/script&gt;
      &lt;script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.2.0/js/bootstrap.min.js"&gt;&lt;/script&gt;
      &lt;script src="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-table/1.8.1/bootstrap-table.js"&gt;&lt;/script&gt;
  &lt;/head&gt;
  &lt;body&gt;
      &lt;div class="container"&gt;
          &lt;h1&gt;Group Columns&lt;/h1&gt;
          &lt;p&gt;Use &lt;code&gt;rowspan, colspan&lt;/code&gt; options to set the group columns header.&lt;/p&gt;
          &lt;table id="table" data-toggle="table"&gt;
              &lt;thead&gt;
              &lt;tr&gt;
                  &lt;th colspan="2"&gt;Item Detail&lt;/th&gt;
                  &lt;th data-field="id" rowspan="2" data-valign="middle"&gt;Item ID&lt;/th&gt;
              &lt;/tr&gt;
              &lt;tr&gt;
                  &lt;th data-field="name"&gt;Item Name&lt;/th&gt;
                  &lt;th data-field="price"&gt;Item Price&lt;/th&gt;
              &lt;/tr&gt;
              &lt;/thead&gt;
              &lt;tbody&gt;
              &lt;tr&gt;
                  &lt;td  style="border: 1px solid black"&gt;1&lt;/td&gt;
                  &lt;td  style="border: 1px solid black"&gt;2&lt;/td&gt;
                  &lt;td  style="border: 1px solid black"&gt;3&lt;/td&gt;
              &lt;/tr&gt;
              &lt;/tbody&gt;
          &lt;/table&gt;
      &lt;/div&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>and it is shown in the following JSFiddle <a href="http://jsfiddle.net/mwe2ufzg/" rel="nofollow">http://jsfiddle.net/mwe2ufzg/</a>.</p>