Dual boot, the same disk, two partitions, main system and safety copy

[fonon]

Hello,
I want to have a copy of main system (Windows 10 x64 pro) on the second partition of the disk. The booting of both systems will be controlled by external bootmanager. What and how do I have to change the copy of the system to start correctly from the second partition?
f.

 

[hang-the-9]

It is much easier and safer to do a clone of the disk to a second hard drive and then select the boot drive when the computer turns on. Messing with disk partitions can easily make even the original partition not bootable.