I cannot help you with internal organization issues ;-)
If you really want to sort this on your own you could backup/export your
mail data to a pst-file, bring it home and run a duplicates remover
against it there. Then bring the pst-file back to work, empty your mailbox
and restore the pst-file to your mailbox.
For more instructions see on how to backup/export and restore your data
see;
http://www.howto-outlook.com/howto/backupandrestore.htm