title: Browser tools detect CSS twice
body: <p>When in the Element section, in the right panel, a CSS set of properties is detected twice:</p>
  
  <p><img src="https://i.imgur.com/kBGwDD1.png" alt="a busy cat"></p>
  
  <p>Same CSS file, same line number, I have only one file named commonCSS. It happens for some elements but not for all. What is going on?</p>
  
  <p><strong>EDIT:</strong> I tried it with Firefox &amp; Chrome so it's not browser related.</p>