A relevant question
Getting back to the original question...which caught my attention because a) I'm a student of marketing and b) I'm cheap!
From a customer viewpoint, I find it quite relevant to know which agencies are owned/operated by the same pimps. Normally, I would expect pimps that operate more than one agency/brand to design their offering so as to go after different segments of the market, as in the Honda/Acura analogy. However, I would also expect girls who usually work the high end of the market to occasionnally (when in dire need of cash, say) work the lower end. These are buying opportunities, that some unrepentant bargain hunting clients want to know about! Naturally, it is not in a $300/h SP's interest to let it be known that she can occasionnally be had for significantly less. Nor is it in the pimp's interest, because that would hurt his high-end brand.
By monitoring all agencies under the same or associated management, it is easier for johns to spot those opportunities. That is why the original question is quite relevant, contrary to what several posters are claiming.
JB
PS: Incidentally, on a personal note, I stopped partaking in the hobby about two years ago since I fell in love (yes, I dare use the word) with a civilian. Yet I remain interested in the hobby as an onlooker.