This relates to the way Less itself works with mixins, and it's the only thing I don't like about the refactor. Less will not replace a mixin, it will simply shove any related mixin found into scope. (This dirties things up a bit, and is bothering me enough that I've started writing my own re2c lexer/lemon parser for stylesheets so I can copy the functionality I like from less but spit out cleaner stylesheets.)