I created a new course in Moodle and saved a file resource. I took the "Raspberry Pi - Project Book v2" again. The file has 46 MB. https://www.raspberrypi.org/magpi-issues/Projects_Book_v2.pdf
I made a backup in Moodle which has 41.8 MB. I did this to see how Moodle will save the resource. Then I saved the same file again within a folder resource. I have two resources in my course. And I made a backup again ... 41.8 MB for both resources. Moodle uses a file management and does not save the same file twice.
In the mobile app I deleted all memory for the website. I logged in and needed 670 kB for this website in the app. I downloaded both resources into the mobile app ... it needed 45.9 MB for the first resource and 91.2 MB for both resources. The app downloaded and saved the same file more than only once.
This takes double time, double download data and double memory size in the app. Is there any way to change this fact? I do not know if the files are marked with a hash string or something else.