Not all double-bitted keys operate two sets of levers. In many (safe-) cases, the levers are not spring-operated, and thus the "backside" prevents overlifting of the lever when you turn the key. Post a picture of the lock and key you have, and we will be able to give you a better answer
Picking lever-locks is not that hard, you just take a good tool, plenty of time and a fair amount of skill. Before you know it,- you´re in
Ed