Is my backup scheme to elaborate?

I have two PCs backed up with Active Backup for Business and a Mac backed up with Time Machine. I also have other shared folders. I have snapshots turned on going back at 5 daily and 3 weekly snapshots. I am using Hyper Backup for all of the shared folders and applications with a rotation setting of Smart Recycle and a maximum of 90 versions.

  1. Is using both Hyper Backup and Snapshots overkill?
  2. Do ABB, Snapshots, and Hyper Backup all do de-duplication? Is it global? If I have a large file on both of my PCs, does DSM only save one copy?
  3. last June, my main NAS had over 8TB of data, due mostly to too many snapshots, I think. Today, it has a total of 6.4TB but my remote, backup NAS has 8.6TB of data almost entirely from Hyper Backup. How can I explain this?