My guess here is that MAPI/EWS (Outlook, AppleMail, emClient) is in fact the previously existing EWS, and should be named only "EWS".

Where MAPI (Outlook 2013+ for Windows) is the new mapi that also uses some EWS as I understood.

So maybe this one should be named MAPI/EWS or only MAPI.

But then as two different options uses EWS, isn't there a possible conflict to have two app passwords for the same protocol (EWS) ?

Without digressing too much, why do we now have different passwords for each protocol?

I think this is only when you enable 2FA auth for the account. There must be a reason for it, but I really have no idea.

App passwords happen when you enable 2FA. 

Thanks for confirming!

The MAPI/EWS app password should be the correct setting to use.  Outlook/MAPI uses EWS to get some information MAPI doesn't supply natively.  I think the the MAPI (Outlook 2013+ for Windows) is one of the older app password settings.  Hey Chris can you send me that user's settings.json file?  My guess is we're not removing the old setting so it still shows up in webmail.  If I can view the file then we can clean this up in a future release.

We were able to reproduce it without needing the settings.json file for the user.  In the next beta build you will no longer see the MAPI (Outlook 2013+ for Windows) app password anymore and should just use the the MAPI/EWS option.  Thanks for reporting this issue.