logo appears twice on pages

Hi there,

Have you solved this?

I'm only seeing one:
http://www.screencast.com/t/GgXXmUYWLUNE

If you are referring to the one showing up in sticky navigation, that would be navigation logo:
https://docs.generatepress.com/article/navigation-logo/

Thanks. if you click on "About," there's a dropdown menu with pages for "Submissions" and "About us." that's where I'm seeing the double logo.

That looks like it's added as featured image:
https://docs.generatepress.com/article/adding-featured-images/

Ok thank you, I removed it. That brings me to another question - how do I include a preview image for the website when it's shared on other sites (not individual posts but the main site)?

Thank you!

You would need a plugin like YoastSEO.