Taking a risk with this.

How do you know what items are duped and what arent? Most people like to try and upgrade equips, in or buy things in FM because they like how it looks, or like to collect chairs, how do you know any of them AREN'T duped? you don't, not all of them anyways, sometimes / very rarely you can tell, but most of the time you would never be able to know. You could be using duped items right now, unless you made them all yourself.

I posted a situation similar to this in Phantasy star, so I already solved this question.