This is just a Warning, that has been around as long as Omniback/Data Prtector, and is mostly found when backing up UNIX-based systems
In the old days, everything existing only on the '/' mountpoint, with a number of sub-directories. Then, along came Logical Volumes, where you could mount directories as a file system
However, DP still treats these directories the same way, and when DP realized that a directory is its own Mountpoint, and not just a sub-directory of '/', this Warning is produced
Look carefully at your session report, and I would be willing to bet that most, if not all of these warnings are coming from the '/' Mountpoint, the the directory being complained about is backed up at some other point in the backup
This is not harmful just irritating. If you want to get rid of these warnings, in the Backup specification, pick the '/' object, expand it, and uncheck any sub-directory that has its own Mountpoint