Eric's right, people can thwart most reasonable efforts he or we make to
reduce the problem of duplicate names.  However, I still maintain that
reminding people that they're naming a new global list the same as some
existing global list might:
 
a) point out to some people that a list they meant to be private is global
 
or
 
b) point out that there is a list already, and wouldn't they rather find a
new name?
 
The glass is half full, the glass is half empty.  Is reducing accidental
duplication enough of an improvement to be worth Eric's time?  It's easy
for me to say, I'm not Eric.  :-)
 
Nick