Once asked to remove on the pages of one WordPress site repeated headlines.
After viewing the code, noticed that they are adding the plugin Yoast SEO, edited in its settings Titles & Metas – Yoast SEO line:
%%title%% %%page%% %%sep%% %%sitename%%
But it did not turn out very nicely, because the plugin sometimes missed the space after the hyphen, so I returned it as it was.
I fixed the error by commenting out the following line in the code of the active template (layout-head.php file):
// bloginfo( 'name' );
After that, the title of the pages was displayed correctly.
P.S. If you disable the Yoast SEO plugin, the above line will need to be uncommented back.
If the topic is not self-explanatory, then probably after the appearance and installation of its update, the layout-head.php file will return to the original state.