Deleted files magically reappear - can someone explain this?

I have a user share comprised of two disks. I want to put one in cold storage (it's all backed up files).

Here is the layout:

Share:

Backup1/

backups\

Tower\

Home Video\

dashcam\

Backup1 contains disk1 and disk3 only

I want to move all the files and directories in Home Video/ from disk1 to disk3 EXCEPT dashcam/

To make this simple, I decided to move dashcam/ up one level and then move all the other directories

in Home Video\ from disk1 to disk3

So I executed:

mv /mnt/user/Backup1/backups/Tower/Home\ Video/ ..

then I moved all the other directories from disk1 to disk3

mv /user/disk1/Backup1/backups/Tower/Home\ Video /user/disk3/Backup1/backups/Tower

Note that in this case I moved from disk to disk not within the share.

I expected that the move within the share would have moved the same named directories on both disks.

But then I got a warning that I was running low on space on both disks. In fact, not all of the files in the dashcam directory

had been moved up. Checking, I found that some 681 GB had been left on disk1 and 427 GB on disk3!

Doing a careful check, I discovered that these leftover directories actually had copies of files that had supposedly been "moved" up one directory

level!

In other words, some 600 GB of files were both in /mnt/disk1/Backup1/backups/Tower/dashcam and /mnt/disk1/Backup1/backups/Tower/Home\ Video/dashcam! and the same on disk3. I should have stopped at this point but I thought: OK I will just make sure that all the files are actually duplicated and then just delete the extra directories. I did this. I checked and found duplicates of the all the files in /mnt/disk1/Backup1/backups/Tower/Home\ Video/dashcam were duplicated in /mnt/disk1/Backup1/backups/Tower/dashcam so I did

rm -rf /mnt/disk1/Backup1/backups/Tower/Home\ Video/dashcam

and the same on disk3 and Voila, I now had about 500 GB free on each disk.

Case over right?

Nope. Next day, I check the Unraid main GUI page and find that each disk on has 81 GB free! What the hell? So I checked and lo and behold, all the files I deleted are back!

I know this has been a long post but I am hoping someone can tell me what happened here and how to fix it.

I am starting to think I don't know how Unraid works at all.

Thanks.