From the feedback form:
"184.108.40.206. Duplicating Existing Sections, Subsections, or Units
I don't see any duplicate button anywhere. Does this feature actually exist? A screenshot would help. "
Text of 220.127.116.11. Duplicating Existing Sections, Subsections, or Units:
To add a section, subsection, or unit by duplicating content that already exists in the course outline, select the Duplicate icon for the item that you want to duplicate. You see a Duplicating indicator at the bottom of the Studio page.
Duplicated items are added to the course outline immediately below the original item, with the name “Duplicate of <original item name>”.
Duplicated items inherit the release date of the item that they are duplicated from, but you must explicitly publish duplicated subsections and units before they are visible to learners. For more information about release statuses and visibility of sections to learners, see Sections and Visibility to Learners.
Add either a screenshot or a description of the Duplicate icon to developing_course/course_outline.html#duplicating-existing-sections-subsections-or-units.
My suggestion: rather than addressing specifically "duplicate", under "Navigate the Course Outline" add a subtopic to show the available controls in the course outline toolbar, including basic settings, visibility, duplicate, delete, drag and drop. Also recommend waiting until "Move" () lands, so that the Move icon is included in the screenshot.
Done as part of adding B&R doc for "Move" ()