I don't do anything special to rinse my gear, the wetsuit and regulator have been in the same water for the same dive, I am not going to kid myself into thinking that they need to be separated for rinsing....
Maybe you are missing the point, or else I'm missing yours. The wetsuit and the reg may have been equally dirty after the dive (if you haven't peed in the wetsuit, and I'm assuming you have not peed in your reg), but you want your reg as clean as possible after a dive (to avoid salt buildup and corrosion) whereas your wetsuit doesn't care much how clean it is (others might of course). So you want to rinse the reg first, in the cleanest possible water, then the wetsuit.