I don't know of any reason why a double dimmer switch panel should be any different from a single one. There are however different types of dimmer circuit and it is possible that your single and double units are from different manufacturers and thus different inside?
Either way it strikes me that these expensive low-energy bulbs that are supposed to work with dimmer units should clearly promote what they will / will not work with.
Personally I've decided to 'suffer' continued use of old-style conventional bulbs in my dimmer-driven circuits until the technology is a bit more mature and the prices of the bulbs come down - which I reckon will happen before the end of 2009.