The identd reply is returned using a program, that runs as root. This is needed, due to the low port number used.
This proram, will lookup the username of a person using a particular IP and PORT, connecting to a particular IP and PORT, and return it to the requeting server (after a few more security checks).
As such, it will allways return your shell login name.
There are some identd demons about, that allow you to change your ident reply, based on the host you are connecting too (based on rules). Though to use these, the server admin has to install them.
This is not very likely, as the server admin can track system abuse by the identd reply.