Does anyone know if you have more than one casting agency?

Doesn't make a not a sense actually. There is confusion here regarding a "casting agent" and a "theatrical agent". All performers are no the books of LOTS of "casting agents", but should be on the books of only one "theatrical agent". The casting agent is the company, such as Prue's Zoo, that actually cast the project. Say I make baked beans, and want to make an ad. I'd engage an advertising agency, they'd engaged a film production company. They would then send briefs to a casting agent. The casting agent sends briefs to the theatrical agent, who submits talent from their books (actors they represent) to be considered for an audition. The casting agent conducts the auditions - auditioning talent the theatrical (otherwise known as a talent) agent has submitted. The artist is represented by the theatrical/talent agent, not by the casting agent. The casting agent conducts the auditions and makes recommendations to the client (advertising agent, film production company, television network etc...) as to who is suitable for each role. Only being known to one casting agent will really limit the number of jobs you're likely to audition for.