I didn't say that your experience on the Rocio del Mar wasn't remote, although the Socorro's would be more so, but the point is that, for many reasons, we don't allow doubles. It's a boat management practice. It has served us well for many years, and the call for change comes from a very few, not from the majority. Perhaps Dora hasn't seen the number of really close calls I have, some based on equipment configuration.
5 years ago there was a hearty call for me to do tech diving. I invested heavily in the gear, including boosters and cylinders and bank bottles and all of the equipment I would need to have a real liveaboard tech boat. One where anyone in the world could come and have rebreather supplies and spares, rental doubles, anything you might need to fly in and go on some world class wreck dives. I invested well over 75 grand in tech training, crew training, material and equipment. I threw open my door, hung out my shingle, and was open for business. The door is now faded, the shingle has cobwebs, and we run maybe one trip per year. Why? Because it's too expensive, or scheduled for the wrong week, or maybe next year.
Now, folks are calling on me to embrace sidemount doubles. I think I'll wait and see.....