That stinks.
I've been on Lunesta, Ambien, Rozeram, Klonopin ...... I think that's it. They've all stopped working for me. Both the lunesta and ambien worked for quite some time for me but eventually just quit. It's very frustrating I know. I just really don't sleep much anymore.
You probably know this but you shouldn't double your dose of anything unless your doctor prescribes it. I'm not saying I'm perfect ....... in fact I'm guilty of it on the Lunesta too. I just recently told my pdoc about it and she said "Don't do that!".