Visual editor and Syntax highlighter box shown at the same time

I noticed that sometimes the Visual editor and the Syntax highlighter box appear both at the same time. I tracked down the issue and I found it depends on the fact that newly created users do not have the usermeta wp_user-settings set in the DB, and as a consequence they do not have the cookie named wp-settings-XX (where XX is the user ID) with the value editor=tinymce. This causes the Syntax Highlighter to appear together with the visual editor (I suppose it uses the wrong default when the cookie is missing).

https://wordpress.org/plugins/html-editor-syntax-highlighter/