Duplication is not bad in itself. It could be another way of saying "flexibility". For instance, the keyboard shortcut for "folder up" is "alt+up", and you could call it duplication as well. There are cases when duplication is redundant and confusing, and in other cases it's a good and useful thing. 

[This question][1] might be relevant too.

BTW, I think "duplicity" means "hypocrisy" rather than duplication :)


  [1]: http://ux.stackexchange.com/questions/3956/is-it-better-to-have-more-than-one-way-to-navigate-to-functionality-or-only-one-w/3957#3957