How to fix duplicate users folders for one user after restoring from TimeMachine backup? "JohnSmith_1"

move are user contents from incorrectly named JohnSmith_1 folder to JohnSmith folder.

Don't do any of that since it is likely to screw things up. Dragging User folder contents from one to another is not the right way to do it, and is certain to result in incorrect file permissions. Instead, rename the one named JohnSmith first, using any arbitrary name. The only reason for doing that is in preparation for renaming the JohnSmith_1 User folder — the one you want to use — which we will be doing presently.

After renaming the JohnSmith folder, perform the following exactly as written:

Change the name of your macOS user account and home folder - Apple Support

Pay attention to the boxed note at the beginning. Apple does not draw attention to such things unless they're really important, and this one is really important. Yes you will need to create yet another, temporary Admin User Account as a prerequisite. It will exist for the sole purpose of renaming the User Account you wish to use — which again I am assuming will be JohnSmith. That's the reason you need to rename that User folder first.

As you follow those Apple Support instructions, if you have questions please stop and ask first.

Assuming all goes well you can eventually delete the temporary Admin User Account according to Delete a user or group on Mac - Apple Support.

At the Login screen, do you see both users?

If you just see the one user account, that's good. You can safely rename the folder in Users named JohnSmith. Rename it in the usual fashion. You will need to authenticate which is normal.

If you see two separate User Accounts at the Login screen don't proceed any further. Also please confirm the JohnSmith folder contains a Library folder, an empty folder labeled 'Misc.' and nothing else.

I assume you want your normal User folder to bear that name and not JohnSmith_1, so give the JohnSmith folder an arbitrary name that we will later change to JohnSmith.

No risk, since that folder's contents will remain unchanged, just under a different name.

I understand your reticence to disregard its contents and I'm not advocating that. The folder's contents will remain unchanged. I doubt they will be necessary but I am just as conservative about not deleting anything unless I'm certain I no longer need it. Even then, you will have the Time Machine backup as a safety net.

Nothing is hidden by default; if there were any other meaningful contents in that folder they would have a "prohibited" symbol meaning they are inaccessible.

Thank you for triple-checking. I don't like being only 99.999% certain either.