When uploading a file with an original filename identical to that of a file in the same folder, Kollaborate will automatically assign the new file as a version, or revision, of the existing file.
When a file has more than one version available, a colored circle will appear next to its filename on the Files page showing a number. If you click that number you will be able to view all of the versions of that particular file.
Versions are also shown on the Player page under the title. You can use the dropdown menu to switch between versions on the fly.
You can use the source dropdown menu on the Player page below the comment box on the right (by default it says "Current file") to view comments from an earlier version. This allows you to double-check that notes from a previous version have been addressed in the latest one.
Manually managing versions
To combine multiple files into a single version stack, select them on the Files page and click Combine Versions at the top of the page. The version numbers will be assigned to the files according to their upload date, so the newest file will be considered to be the latest version.
Note: You cannot combine folders or aliases into a version stack.
To remove files from the version stack and make them independent, click the colored number next to the file's title on the Files page, then select the ones you wish to separate and click Make Independent at the top of the screen.
Note: You cannot make the original file (i.e. Version 1) independent while other files still exist in the version stack. The only way to do this is to select all files, make them all independent and then manually recombine the other files into a new version stack.