This RT extension adds a "Merge Users" box to the User Administration page, 
which allows you to merge the user you are currently viewing with another
user on your RT instance.  It also adds MergeInto() and Unmerge() functions to 
the RT::User class, which allow you to programmatically accomplish the same
thing from your scrips.  It also provides a version of CanonicalizeEmailAddress,
which means that all e-mail sent from secondary users is displayed as coming
from the primary user.

To install:

    perl Makefile.PL
    make install

For 3.8

    Add RT::Extension::MergeUsers to your /opt/rt3/etc/RT_SiteConfig.pm file
    Set(@Plugins, qw(RT::Extension::MergeUsers));

    If you have more than one Plugin enabled, you must enable them as one 
    Set(@Plugins, qw(Foo Bar)); command

UPGRADING

If you are upgrading from 0.03_01 or earlier, you must run rt-upgrade-merged-users
This script will create MergedUsers Attributes so RT can know when you're looking
at a user that other users have been merged into.  If you don't run this script,
you'll have issues unmerging users.  It can be safely run multiple times, it will
only create Attributes as needed.