id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
769	disallow variables that differ only in sigils	szabgab		"In beginner mode disallow $x if @x is already in use.

Idea from gaal in a comment 
http://blog.woobling.org/2009/11/restricted-perl.html

Before implementing, please check if there is no Perl::Critic rule for this!"	enhancement	new	major		editor	0.50		usability