Configuration Protection > Main Status ignored with two identical external displays

[anothermh]

I have two identical external displays. I have configured the display on the left with "Set as Main Display" and enabled "Configuration Protection > Main Status". The display on the right does not have either option checked.

When waking from sleep or when undocking/redocking there's a diceroll that seems to determine which display will be the main display. Reinitializing all external displays does not fix the issue; I have to change the main display manually by checking the "Set as Main Display" checkbox again.

[waydabber]

Yes, the dice roll for two entirely identical displays is a longstanding macOS issue. The best approach is maybe not the set as main display but to use the Switch identical displays feature when the dice roll has the wrong result (you can tie it to a keyboard shortcut as well).

[anothermh]

The two displays are identically configured, except one is in portrait and the other is in landscape. Would it be possible for the configuration protection to differentiate them based on differences like this?

[waydabber]

With the latest v3.3.2 internal pre-release (enable this under Settings/Applications/Update) one can set the identification method for the displays to "Basic + extended + port". This should (in theory) make the app identify a display as a specified display only when it is attached to a specific port. This will not solve the macOS mixing the displays up but at least the app should not mix them up. This might not work well with docks and will not work with non-natively connected displays.