Backup And Recover Win7 and Win10 From same computer To One External Hard Drive?

Question

Hi,
I am currently on Windows 7 os.  I would like to create a Windows Backup Image on my external HD. After doing this I intend to move up to Windows 10 os. I would then like to create a Windows Backup Image on the same external HD. So that one external hard drive would then have two Windows Backup Images on it; my Win7 Backup Image, and my Win10 backup image.
Will the Win10 backup image overwrite the Win7 backup image since it's the same PC machine?
If so would a work around be to partition the Ext HD and put each backup image on it's own partition? 
I have read mixed experiences regarding renaming and moving Backup image folders around so am hoping this work-around can avoid both??
And just to confirm; Restoring from a Windows Backup Image is not dependent on the current os you're on - correct?  eg. when I move up to Windows 10 os and say I have issues, then restoring back down to Windows 7 should work - correct? (using the backup image on the External HardDrive)? 
Any advice with the above few questions would be greatly appreciated, thanks!

Referring to question source:
https://social.technet.microsoft.com/Forums/windows/en-US/1603af76-6f3c-4212-b519-c0232a58a93b/backup-and-recover-win7-and-win10-from-same-computer-to-one-external-hard-drive?forum=w7itprogeneral

Answer 1

One of the most important policy of forum is: one post one question. Overmuch question will make your post unclear and lengthy, then some forum users may lose interest in...

For your concern:

Yes, Win7 and Win10 backup images are two completely independent backup images. The different creating time I mentioned is just point to their name, you know, when we create a system image, the image file will be named as a format like: Backup YYYY-MM-DD HHMMSS. You created two image file, of course they have two names, according to the create time, you can which is win7 and which is win10.

>So if for instance in 5 years I decide to make this PC a windows 7 machine, I could restore using the win7 windows backup image that I'm about to create?

Is it possible/done/considered good practice to do the partition idea?

Yes, you could and it is a good idea.

Answer 2

Question 1:

Will the Win10 backup image overwrite the Win7 backup image since it's the same PC machine?

No, don’t worry, Win10 backup and Win7 backup image are independent, they are named by same format but different creating time.

Question 2：

Restoring from a Windows Backup Image is not dependent on the current os you're on - correct?

Theoretically, yes.

Restoring a full image backup will completely overwrite everything that exists on the hard disk, replacing whatever was there before, no matter what it was. The previous operating system, along with everything else on the hard disk, will be overwritten and replaced with the contents of the image backup.

Note, restore a system image is no longer available from the desktop.

Important:

You can’t restore a Windows system image backup on a different PC. Your Windows installation is tied to your PC’s specific hardware, so this only works for restoring a computer to its previous state.