title: Duplicate empty header occur in datatable when enabling scrollX or scrollY when using Google Chrome
body: <p>I have a datatable in my program. And I want it to be scrollable horizontally so  what I did was like this:</p>
  
  <pre><code>var tableI = $('#table_data').DataTable({
      "bLengthChange": false,
      "scrollX": true,
       "dom": 'frtp'
  });
  </code></pre>
  
  <p>It came out like this(as sample output):
  <img src="https://i.stack.imgur.com/vPpTv.png" alt="enter image description here"></p>
  
  <p>It doubled the header. How am I going to fix this?</p>
  
  <p>EDIT:
  Here's another sample:
  <img src="https://i.stack.imgur.com/dhH7O.png" alt="enter image description here"></p>
  
  <p>here's my HTML code:</p>
  
  <pre><code>&lt;table class="table table-striped" id="act_data" width="100%"&gt;  &lt;div style="float:left;width:385px" &gt;
      &lt;button type="button" id="edit_acc" class="btn btn-primary" data-toggle="modal" data-target="#editAcc"&gt;&lt;span class=" fa fa-edit "&gt; Edit Account&lt;/span&gt;&lt;/button&gt;
        &lt;button type="button" id="de_act" class="btn btn-primary" data-toggle="modal" data-target="#DeAcc"&gt;&lt;span class=" fa fa-edit "&gt; Activate/Deactivate&lt;/span&gt;&lt;/button&gt;
        &lt;!-- &lt;button type="button" id="refresh" class="btn btn-link"  data-target="#DeAcc"&gt;&lt;span class="fa fa-refresh"&gt;&lt;/span&gt;&lt;/button&gt;--&gt;
        &lt;a href="&lt;?php echo site_url('admin/homeAdmin/homepage')?&gt;?id=6" class="btn btn-link"&gt;&lt;span class="fa fa-refresh"&gt;&lt;/a&gt;
      &lt;/div&gt;&lt;thead class="header"&gt;
        &lt;tr class="well"&gt;
          &lt;th style="font-size: 14px;"&gt;Employee ID#&lt;/th&gt;
          &lt;th style="font-size: 14px;"&gt;Username&lt;/th&gt;
          &lt;th style="font-size: 14px;"&gt;Account Type&lt;/th&gt;
          &lt;th style="font-size: 14px;"&gt;Status&lt;/th&gt;
        &lt;/tr&gt;
      &lt;/thead&gt;
  
      &lt;tbody&gt;
        &lt;?php if($result != NULL){?&gt;
          &lt;?php foreach($result as $row){ ?&gt;
              &lt;tr&gt;
                 &lt;td style="font-size: 15px;padding-left: 20px;"&gt;
                     &lt;?php echo $row-&gt;employeeID;?&gt;
                     &lt;input type="hidden" name="userID" id="userID" value="&lt;?php  echo $row-&gt;userID;?&gt;" /&gt;
                     &lt;input type="hidden" name="pass" id="pass" value="&lt;?php  echo $row-&gt;password;?&gt;" /&gt;
  
                &lt;/td&gt;
  
                &lt;td style="font-size: 15px;padding-left: 20px;"&gt;
                     &lt;?php echo $row-&gt;username;?&gt;
                &lt;/td&gt;
                &lt;td style="font-size: 15px;padding-left: 20px;"&gt;
                     &lt;?php echo $row-&gt;usertype;?&gt;
                &lt;/td&gt;
                &lt;td style="font-size: 15px;padding-left: 20px;"&gt;
                 &lt;?php echo $row-&gt;status; ?&gt;
                 &lt;/td&gt;
  
            &lt;/tr&gt;
          &lt;?php }?&gt;
        &lt;?php }?&gt;
      &lt;/tbody&gt;
    &lt;/table&gt; 
  </code></pre>