Duplicate class attribute on tag

[tvd12]

Hi, I'm using https://dillinger.io/ to convert markdown to html, but I see we have duplicate class attribute on tag, example:

• markdown code

  #include "EzyHeaders.h"

  I got:

  <pre><code class="has-line-data" data-line-start="1" data-line-end="3" class="language-cpp"><span class="hljs-preprocessor">#<span class="hljs-keyword">include</span> <span class="hljs-string">"EzyHeaders.h"</span></span>
  </code></pre>