I don't understand the title.

It doesn't seem like they are trying to figure out why two copies of outlook are installed, they're trying to figure out why neither is giving them access to their email.

People opening the "wrong" Outlook has been the norm for the last couple of years. Between "Outlook (classic)", "new" Outlook (rolled out with Office 365 clients), and "Outlook" (rolled out with Windows 11) it's been a shit show for a while now.