I've been comparing the options shown in our Moodle 3.1.6 instance with what is listed on the 3.1 Manage roles documentation page:
Could others with this Moodle version please advise whether they have the options listed on that documentation page?
From the page: "'The 'Manage roles' tab contains a list of roles on your site. The edit column contains icons for editing, deleting roles and copying roles, and for moving them up or down in the list (affecting the way that roles are listed around Moodle)."
The Edit column in screenshot below this text doesn't show an icon for copying, just icons for editing, deleting and moving up and down.
The screenshot corresponds to what I see in our instance.