Snapshots restore files on Writetrough Disk

[CyanCetus]

Hello dear support team. My snapshots restore files on Writetrough Disk. Here my thread on forum ​https://forums.virtualbox.org/viewtopic.php?f=6&t=106742

I use two VDI on my VM. First VDI: Normal type. Created for system using (OS, applications, system configuration). I want to take snapshots only from Normal disk type. Second VDI: Write-through type. Created for file storage. I don't want to take snapshot from Write-through disk. But files are restored on Write-through disk... I do not understand anything. Please check me step by step. I will try to be as detailed as possible.

1. I created new VM with new VDI (Normal type for system using). Capacity 30GB. Screenshot ​https://www.dropbox.com/s/gy764nib8kljrdc/Screenshot_8.png?dl=0
2. I created new VDI (Write-through type for file storage). Capacity 50GB. ​https://www.dropbox.com/s/2g2cfr621yuqo93/Screenshot_12.png?dl=0
3. Check attached to VM disks. ​https://www.dropbox.com/s/8ospntq1fx4w9l5/Screenshot_16.png?dl=0 second ​https://www.dropbox.com/s/8zr79tm9zp6a2ny/Screenshot_17.png?dl=0
4. Now I'm install Windows 10 on 30GB disk (Normal type) ​https://www.dropbox.com/s/g0uk8bkozy51scy/Screenshot_18.png?dl=0
5. Initialization wright-trough disk after Windows installation ​https://www.dropbox.com/s/0dnlszujxk5akcw/Screenshot_19.png?dl=0
6. Now I have 2 local disk in Windows Explorer ​https://www.dropbox.com/s/tw8vf0c14dcf18j/Screenshot_22.png?dl=0

Now it will be interesting

7. Create test folders ​https://www.dropbox.com/s/fhv3vg2x9z4gnhv/Screenshot_23.png?dl=0
8. Take snapshot ​https://www.dropbox.com/s/ce1x0r39d34ebfy/Screenshot_25.png?dl=0
9. Test folders deleted using SHIFT+DEL ​https://www.dropbox.com/s/icjf5t3wyjmz4qh/Screenshot_28.png?dl=0
10. Shutting down VM and restore Test 1 snapshot ​https://www.dropbox.com/s/orv5cr5ijt29v65/Screenshot_31.png?dl=0

I expect to restore test folder on only drive C:\ (Normal type)

11. Why test folder restored on Write-trough disk (E:\)? ​https://www.dropbox.com/s/edqmh7ojn7ngmbx/Screenshot_33.png?dl=0