Two Win 10 on one PC

I tried installing two Win 10 on the same harddisk, but that did not work. The second would not install.

Added an extra harddisk and installed the second Win 10 on that.

After that the PC automatically booted using the last installation.

Only way to boot using the first was to interrupt the BIOS to change boot drive.

Windows Boot Manager did not appear automatically giving an option to choose between the two installation.

Force activation of Windows Boot Manager:

  1. Start Command Window as administrator: Type “cmd” in search box, right click the command prompt and select “Run as administrator”.
  2. Run command: bcdedit /set {bootmgr} displaybootmenu yes.
  3. Run command: bcdedit /set {bootmgr} timeout 30. (Timeout in seconds. Set to 0 to disable).


Check boot options:

  1. Run command: bcdedit
  2. A list of boot options is listed


Add new option:

  1. Run command: bcdedit /copy {current} /d “Win 10 First” (The name/alias for the option can be anything, and it can be renamed later)
  2. Run command: bcdedit
  3. Check that new option is added and copy identifier to clipboard


Change drive for the new option:

Check what drive letter is used on the disk where the first option is installed and change drive letter to that (e.g. F):

  1. Run command: bcdedit /set <GUID> osdevice partition=F:
  2. Run command: bcdedit /set <GUID> device partition=F:

<GUID> is the id copied to clipboard above.