Who does the ID belong to?

Hello,

As most of us here probably have already experienced, we are seeing a spike in channel use (we have 3 corporate channels). After reviewing the "Channel use" sessions, we have identified a number of IDs that we do not recognize in the Management Portal. Any tips as to how to validate they are really company users? Is this an issue where maybe the user is in a group that isnt shared with the rest of us admins?

Thanks for the help!