Duplicate a list
Web & desktop app
To duplicate a list, click and drag the bullet point of the list and hold down Ctrl/Cmd at the same time. The label at your cursor will say "Copy 1 item".
Alternatively, Pro users can customize the "Duplicate current item" shortcut under "Settings" - "Keymap" - "Working with lists". Pressing this shortcut will duplicate the current item you're on.
Unfortunately, there's no way to duplicate a list on the mobile app right now.