There were way more than hundreds duped... There were thousands.. I personally know 4 people that participated in the dupe, including my self. We ran bots for almost two days before jagex caught onto it. Each of us ran more than one bot to accomplish this, resulting in thousands of party hats being duped... Most of the accounts got banned, though a few mule accounts may exist to this day. The bots would trade each other, and put up '0' of the designated hat enough times to fill the trade window, accept, and do so untill the inventory was filled with hats, which would then be deposited in the bank. The first person to know about the dupe, after 6fu, was sorrow; 6fu's IRL mate. He was part of the ichooseyou crew, who was ran and maintained by g0ne.
FACT: Items were being duped months before jagex found out. It was only when the exploit got released publicly that jagex found out.