There's a quirk in the new version of Blackboard. When you do a course copy, Bb copies the course availability settings from your old course to the new course. If your old course is available to students, this would make your new course available before you're ready for students to view it.
In a perfect world, you have already made all your old courses unavailable, but just in case you haven't, please do so before copying Bb containers for the upcoming semester. Instructions for making your courses unavailable can be found at
A word of caution. You may be tempted to avoid this problem by not copying course settings, but this is one of the most important areas to copy, so please make sure course settings is checked when you do a course copy.