Exchange 2000 User Mail Boxes duplicates

In Exchange 2000, when you look at the User Mailboxes showing the sizes
last logged on info.

I see what appears to be a duplicate of the username most of these are
preceeded by a Red circle with a white X in the middle....The options on
these duplicates are REJOIN, PURGE, DELETE.

What are the purposes of the duplicates? and why do they also show a size?

Could this be related to some internal users cannot send mail to external
email addresses.  All user settings in the account are identical to those
that work fine. 4 out of 67 users have this problem.

Note, All of these accounts were automatically created when we did a
migration from Novell Groupwise to Exchange.

Thanks..

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