Yes, you can install two Windows on the same partition. It’s the best and safe method to try new Windows. You don’t have to worry anymore about deleting old Windows files and folders.
Guide to install two Windows on the same partition
<1> Download the Windows 10 ISO file for Windows and extract all the files into a folder. Note you can also use Windows 7/8 ISO image files.
<2> Open Disk Management, click Action, then Create VHD. Use the VHDX file format and assign how large your virtual hard drive should be(25GB is good enough for testing).
<3> Find a location to store the new VHDX(drive with 25GB free space or more), pick a name, click Save and then OK.
<4> When the virtual hard disk has been created. From the Disk Management, initialize the new disk. Right-click the new drive, select Initialize Disk, and GPT, and click OK.
<5> Right-click the unallocated disk space and select New Simple Volume, click Next, Next, remember the new drive letter, click Next, leave the default settings, click Next, then Finish.
<6> Open the Command Prompt as an administrator and select your ‘Sources’ directory where you extracted the Windows Insider Preview ISO file. Example: E:\Windows10InsiderPreview\Sources. Run the DISM command to apply the install.wim image to the new virtual hard drive. Where “E” is the drive letter you assigned to the new virtual hard drive. Type the following command and Enter
dism /apply-image /imagefile:install.wim /index:1 /ApplyDir:E:\ <7>After the DISM complete applying the image to the new virtual hard drive. The next step is to enable dual-boot. To do this, in Command Prompt type the following command and hit Enter bcdboot E:\Windows
Restart your PC and from start menu choose the new Windows. You’ll then need to complete the installation process. For Surface Pro 3, you may need to download the Surface Pro 3 drivers pack.
After installation, now you have two Windows on the same partition. If you don’t like the new Windows, you can delete Virtual partition anytime from your computer, without messing around with old Windows files.