I’m only seeing it once. If you’re seeing it twice it might be because you’re using an Author Bio plugin and have the theme author bio enabled. You can disable the theme author bio from Customize > Theme Settings > Blog.
That is strange that you don’t see it – I have had contributors to my site tell me they are seeing it… it appears at the top of the author page (not on the individual article pages) in dark text followed by the same text in light gray.
I am using an author bio plugin, but I do not “Post Author Box” enabled under the theme settings.