Annette,

The answer to your first question is yes. If you download an older version of a course from the web site and import it into the Author tool, it will replace any existing course of the same title that is already known to Author.

However, the answer to your second question is also yes. If you start Author and rename the course you are currently editing to a new name, then the imported, old version of the course will retain its name and will not overwrite your edited version. Then you will have both versions, which will appear to Author as two separate courses.

I assume that, at some point, you will want to get back to editing your new version with its original name. Here is where we have to be very careful. First delete the downloaded, previous version of the course from Author. This will not affect the version on the web site. Now rename your new version back to the original name. When you do this you must be certain to rename it to exactly the same name as it had originally - same capitalization, same punctuation and spacing, everything. Then upload the new version to the web site. Of course, the version number for this new version should be higher than the one for the older version already on the web site.