<!DOCTYPE html>
<html>
  <head>
    <link rel="stylesheet" href="data:text/css,@font-face {}';">
    <link rel="stylesheet" href="data:text/css,@font-face {}';">
    <script>
      // Force a unique inner for the second linked sheet
      document.styleSheets[1].cssRules[0];
    </script>
  </head>
</html>