Most jacket BCs seem to be designed with the idea that 'more is better'. So there are extra dump valves, D rings, pockets, bells, whistles, vanity mirrors, cup holders, neon accents, zippers, clips, buttons, velcro, ipod docks, facebook apps, GPS systems, extra fries, AC adapters, comfy padding, Christmas tree ornaments, soap dispensers, towel racks, shag carpet, who knows what else.
Sorry about the rant. The right shoulder dump valve is sold as a 'safety feature' or as a convenience, but in truth it's absolutely not necessary and a possible failure point where the air could leak out of your BC. They usually don't mention that part in the shop. It's best to have two options, not more, for dumping air; the LP inflator and a dump valve on the lower portion of your BC, usually on the left hip.
The pull dump that's activated by yanking on the corrugated hose is a particularly stupid bit of engineering, although it's practically universal among jacket BCs. It doesn't make a lot of sense to design something in which the user is essentially try to pull off the weakest hose, especially considering that if it does come off, there is no longer any way to get air into the BC.