[rt-users] User name collision

[Rich West]

I just got our company to migrate over to Request Tracker from an
inferior product, and after a couple of days of good functionality, we
received the following error:
     RT could not load a valid user, and RT's configuration does not
allow for the creation of a new user for this email (dshaw at mydomain.com).

Now, we have had no problems with users submitting tickets... everyone
is allowed to.  I'm fully versed in the internals of RT, so it isn't
like this is something new for me.  So, as I dug in to the issue, I
discovered that the user, dshaw, is listed in RequestTracker with the
email address of dshaw at myotherdomain.com.  The user name in RT is dshaw.

I am guessing that, because dshaw at myotherdomain.com was already in the
system with the RT user name of "dshaw", RT couldn't automatically
create another "dshaw" user with a different email address.

Is this a known issue?  Is this something that can be avoided, and, if
so, how?

-Rich