When you copy entire courses your course name changes to show you which one is the copy and which one is the original. You will need to change the name of the course to remove 'Copy of' and the course URL (where it will display 'copy-of-' before the orignal's URL) before publishing it.
To do this, you must change the course card title and landing page title.
To change the course name:
Go to your Admin Dashboard. Select Edit on the new course.
Under Settings, select Basic.
Edit the Course Name and Course URL with the new course name. Select Save Changes.
This will change the course name and URL but not the landing page header text.
To change the header text on the Landing Page:
In your course, select Landing Page then Banner.
Scroll down to Banner Title and change the title to your desired text. Select Save.
Now both your course card and landing page titles will reflect your updated titles.