Unwanted changes after last update.

Hi, do you mean you don't want to have to log in.. like this?
Sign in User Account Automatically at Windows 10 Startup

I can't say why that changed though.

For some reason I get my name twice at the bottom left of the log-in screen.

I would guess you need to resolve that.
For example, you might need to delete a redundant user account.

First consider how that was created... assuming you haven't specifically created it:

If you read the introductory text to the tutorial carefully, that might give clues E.g. (just part):

If you set Windows to automatically sign in to a user account at startup and ever change the computer name afterwards, then you will see a Other user at sign in that fails to sign in, and you must manually select your account and sign in instead. You will need to repeat the steps below again to fix having Windows automatically sign in to the user account that you want at startup.
Other user can also show on the sign in screen if you set to do not display user names.

** Also see comments following the tutorial- some experiences sound similar to yours.

How do you avoid clean installs in many cases?

The method repeatedly recommended here to provide you a way to protect yourself from the unexpected, and let you restore Windows or any imaged disk or partition to a previous good working state is to routinely use disk imaging - e.g. Macrium Reflect (free).

As you don't want to try to solve your problem, and if either (e.g.) uninstalling the most recent update (guess) or using a System Restore point (unreliable) doesn't help, I would, in your situation, have restored Windows from a recent disk image.

First make sure you've backed up anything you need from your C: partition (If you image it, you can later extract any file you want from the image file).

Then clean install- which means deleting all partitions which were created when Windows was installed- e.g. 4 for a UEFI installation. To clean install you need to create a bootable Win 10 disk. Tutorial available.

I get my name twice at the bottom left of the log-in screen.

This would mean that you used to have a Local account with your user name and password, During the Update, it asked you if you would rather use a Microsoft account. If you typed in your Microosoft Email or Phone# then you would be presented with two login accounts with your name at the bottom left.
Find out which account has your password that logs you in. If it is an Admin User Account, you can Delete the Microsoft Account or verse visa.