title: Can a HTML element have multiple unique ID attributes?
body: <p>Needed to know if an HTML element <strong>can have multiple attributes of ID's</strong>, for instance :</p>
  
  <pre><code>&lt;input type="text" id="identifier1" id="selector1" /&gt;
  </code></pre>
  
  <p>As I needed to <strong>clarify</strong> this statement mentioned about selectors at <a href="http://www.w3.org/TR/selectors/#id-selectors" rel="noreferrer">W3 website</a>.</p>
  
  <blockquote>
    <p><em>If an element has multiple ID attributes, all of them must be treated
    as IDs  for that element for the purposes of the ID selector.  Such a
    situation could be reached using mixtures of  xml:id, DOM3 Core, XML
    DTDs, and namespace-specific knowledge.</em></p>
  </blockquote>
  
  <p>The Possible duplicates which people are referring, states question for this syntax</p>
  
  <pre><code>&lt;input type="text" id="identifier1 selector1" /&gt;
  </code></pre>
  
  <p>which is different than syntax that I am asking.</p>