The dual-licensing in much module boilerplate these days is unnecessary. You can simplify your licensing by using only the Artistic License 2.0.
There are plenty of modules out there that license themselves "under the same terms as Perl itself", and there are problems with that approach. For the past year or so I've been using the approach of being explicit about "Artistic or GPL, your choice", but that's unnecessary, too.
According to Allison Randal, one of the architects of Artistic License 2.0, "Artistic 2 allows for any GPL-like license, not just GPL 2. Specifically, it allows for GPL 3 or later, or a completely non-GPL copyleft license. So, the dual license is unnecessary."
From here on out, my code is going to say:
=head1 LICENSE Copyright (C) 2010, Andy Lester, This module is free software. You can redistribute it and/or modify it under the terms of the Artistic License 2.0. This program is distributed in the hope that it will be useful, but without any warranty; without even the implied warranty of merchantability or fitness for a particular purpose.