S
In a 'traditional' hard copy system, part of the reason why you also control the distribution is to overcome the problem you are facing now. I would check the illegally copied document to determine from which of the controlled copies did it originate from and then go after the person who holds that controlled copy. In other words, control should be centered around the few and known holders of the 'controlled' document.
Appears like a system problem to me.
Appears like a system problem to me.