title: W3C validator complaining about duplicate div
body: <p>I use a <code>clear</code> div in several places in a single HTML file, a la:</p>
  
  <pre><code>#clear
  {
      clear: both;
  }
  </code></pre>
  
  <p>usage:</p>
  
  <pre><code>&lt;div id="clear"&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>But W3C's HTML5 validator appears to be complaining that each subsequent use after the initial use is a "duplicate ID":</p>
  
  <p><img src="https://i.stack.imgur.com/XLpSr.png" alt="le validation errors"></p>
  
  <p>Why isn't this valid? How are you supposed to use <code>clear</code> divs multiple times on a single page if it isn't technically valid?</p>
  
  <p>Note: this is mostly just an informative question, my HTML renders fine on all modern browsers, and given that this is the only error the HTML5 validator can find, I don't reall care, but I'd just like to know why this is considered to be a problem.</p>