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I have created two IMAP email accounts on Outlook 2016 in order to receive mail sent to each of the email addresses on its corresponding Inbox folder, but mail sent to any of them appears always on both Inbox folders.
As far as I know, if you want two Outlook.com accounts to receive the same email, you can add the other account as an alias. More information, see: https://support.microsoft.com/en-gb/office/add-or-remove-an-email-alias-in-outlook-com-459b1989-356d-40fa-a689-8f285b13f1f2.
This will give you an additional email address that uses the same inbox, contact list, and account settings as your primary email address. Outlook.com lets you have multiple aliases associated with a single account, and you can choose which email address you send email from.
If the IMAP account does not meet your needs, it is recommended that you use inbox rule or search folder to automatically sort emails sent to different addresses into their own folders for easy viewing.
In addition, this issue seems to be related to Outlook.com accounts, you could post your case in dedicated forum for Outlook.com for more professional advice.
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