Two Identical Monitors Plugged in with USB-C
I've experienced this as well, and there are a few fixes that I've found.
Solution One
This fix involves involve running macros on startup. Here's a link to the &quot;Keyboard Maestro&quot; method which includes using a utility called displayplacer on github.
Solution Two
It's possible this is related to spaces/mission control behavior. One easy thing I would suggest is going into System Preferences -&gt; Mission Control and uncheck &quot;Automatically rearrange Spaces based on most recent use,&quot; assuming that is checked. This may solve your problem, maybe not.

Solution 3
I'm a bit dubious about this one, but it's easy and worth a shot. Basically, you need to remove the Caches folder in your User Library folder. You can try to do this with finder, but I suggest opening terminal and entering
sudo rm -rf /Library/Caches/ColorSync
rm -rf ~/Library/Caches

And then restarting your computer. Please note that you may clear your user-specific caches with that second command, which include caches from other Applications and things like iCloud. These are caches, so you shouldn't experience any real data loss, but certainly be a bit cautious with this one.
I wish there was an easy fix. Hopefully the mission control solution works for you, but this seems like it's been a problem for several years.