How do I view two accounts in my Inbox at the same time

I recently started monitoring a second email address at work via Outlook 2007. At first I had to switch users and log in as the second person to view their mail. I have figured out how to make my main account be a delegate and view the other Inbox via File>Open>Other Users Folder and this works better however I noticed on a different computer here in the office a user can view two different Inboxes at the same time Capture.JPG
Nobody at the office seems to know how this was done. Does anyone have any ideas?

Thanks!

If you have this permission "At first I had to switch users and log in as the second person to view their mail." then you should be able to do this.

Add another person's mailbox to your profile

If you frequently work with someone else's Exchange folders, you probably will want to add the other person's Exchange mailbox to your Outlook profile. Doing so will automatically open the other person's mailbox each time you open Outlook. The other mailbox appears in the Navigation Pane beneath your Exchange mailbox folders.

https://support.office.com/en-us/art...8-6d009eb4b572