does bradley make 2 element converson kit 4 the bradley 6 rack digital smoker 120v
I don't think Bradley endorses adding the second element. But here are some threads on doing it.
http://www.susanminor.org/forums/showthread.php?572-Additional-Heating-Element-Modification
I would suggest you read those then post any questions you may have. A lot of people have done the mod and are more than willing to help.
Also you get better responses if you post your question in one place only