Does clickbank allow you to join up with other affiliate networking sites while being listed in clickbank's marketplace? If they do allow this, what other affiliate networking sites are similar to clickbank? Also can you use clickbank's payment processing for getting sales with other affiliate networks? If they don't allow you to be signed up with 2 affiliate sites couldn't you theoretically just copy your landing page/marketing materials and all that stuff to a different domain and join with other affiliate networks using the same approach just a different domain name?
I think they do, however these are questions you should ask directly to Click Bank. I don't know if anyone here can clear those concerns up for you.