Strapworks 1" webbing is fine for two people. My girlfriend and I routinely get in the hammock together, but I do make sure I've got the correct webbing with me.
I have had webbing fail. Once, it was in the form of a gash. It was Strapworks webbing and it wasn't the webbing's fault. I had a steel ring break and the sharp edge ripped down the center of the webbing. Genuine Draft and I had to hang from that webbing for a few days until we got into the next town. The gash/tear was right down the center of the webbing, maybe 7" long. It held both of us even in that condition. Pretty sure I still have it, I'll try to remember to take a picture if I can find it. Point is, the stuff is tuff! Strapworks.com is the place to get your double sleeper webbing IMO.