The rules currently allow agents to speak to as many clubs about their client, the clubs just can't put their money where their mouth is and offer a contract for consideration. It's a huge grey area and why it keeps on happening. Who dobs in an agent if they take offers from clubs? The only people that would know about it are the agents, recruitment guys and maybe the player. It's not in their interests to disclose that they've broken the rules.
I'd like to see the NRL rule out independent agents. Make all agents NRL employees, on a base salary paid by the nrl, with no commissions from deals struck. Their job is simply to negotiate the best deal for their client, if there's no incentive in it for them to push agendas then it becomes a non issue.