Groupfolders for which a user has no reading-rights (Advanced Permissions) can still be copied and read out!

Example:

Employee list / NC users:
MA1 site manager
MA2 accountant
MA3 project employee Lisa
MA4 project employee Hans

NC folder structure (group folder):

Group folder company location Berlin
  ├── Administration
        ├── accounting
  ├── projects
        ├── Project A
        ├── Project B

The following should be set via “Advanced Permissions”:
Write and read rights to all folders should have: MA1 site manager
Write and read rights to accounting folders should have: only MA2 accountant
Write and read rights to project folder A should have: only MA3 project employee Lisa
Write and read rights to project folder B should have: only MA4 project employee Hans

All of this is easy to set using the “Advanced Permissions” in the “Groupfolder”.
However…
For the root folder “Group folder company location Berlin”, all NC-users must have at least reading rights, otherwise you won’t see a folder at all…

“MA4 Projektmitarbeiter Hans” does not initially see the “Administration-Accounting” folder.
However, if he copies the complete root directory “Group folder company location Berlin” and inserts it into another of his own folders, all directories and their contents are visible to him.

Can this copying of the “invisible” folder or in general be prevented somehow?
How would you solve this problem?

Thank’s for the Tipps. Matthias