Re: two\dual four\?
I want to quibble with the use of the word "nature" to describe something that has two parts. I know that wasn't the point of the question, but something that has a dual nature can be seen or used by people in two different ways or acts on other things two different ways. Simply having two parts doesn't give something dual nature.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.