title: regex to ignore duplicate matches
body: <p>I'm using an application to search this website that I don't have control of right this moment and was wondering if there is a way to ignore duplicate matches using only regex.</p>
  
  <p>Right now I wrote this to get matches for the image source in the pages source code</p>
  
  <p>uses this to retrieve srcs</p>
  
  <pre><code>&lt;span&gt; &lt;img id="imgProduct.*? src="/(.*?)" alt="
  </code></pre>
  
  <p>from this</p>
  
  <pre><code>&lt;span&gt; &lt;img id="imgProduct_1" class="SmPrdImg selected"     
  onclick="(some javascript);" src="the_src_I_want1.jpg" alt="woohee"&gt; &lt;/span&gt;
  &lt;span&gt; &lt;img id="imgProduct_2" class="SmPrdImg selected"     
  onclick="(some javascript);" src="the_src_I_want2.jpg" alt="woohee"&gt; &lt;/span&gt;
  &lt;span&gt; &lt;img id="imgProduct_3" class="SmPrdImg selected"     
  onclick="(some javascript);" src="the_src_I_want3.jpg" alt="woohee"&gt; &lt;/span&gt;
  </code></pre>
  
  <p>the only problem is that the exact same code listed above is duplicated way lower in the source. Is there a way to ignore or delete the duplicates using only regex?</p>