Ok I just tested different things and I'm not sure if I understand the bug correctly.
@rocked23 on your website I don't see doubled headlines
that the content, which has H1 and H3 is now doubled on the site.
Did it look like this?
<h1>my headline</h1><h1>my headline</h1>?
Maybe the seo tool has looked through the desktop version markup and custom phone layout markup. Both co-exist on a page that has a custom phone layout.
If you could recreate that bug and let me know exactly how you recreated this, that would be helpful. And a page where the bug exists would be helpful.
@Marvic please post a link and screenshot of where you experience the problem
I tried out changing textformats to h1, h2, h3 and changing a paragraph format to a headline format and none of these steps produced any bugs for me.
Please note once you have changed a format to h2, h3, h4 or changed a format type, you need to re-apply that textformat to the pre-exisiting text that uses that format in the gridder. This way the pre-existing texts that already used that format will change to h2, h3, h4 or to a different type.