if you have passed the any one of the module then you need not to give exam for the module you have passed.
but, if you wish to give the exam for both the modules than you have to request to ICSI, that you wish to give exam of both the modules a fresh.
Such a request made to ICSI is not reversed in future, if you wish to avail the benefit of previous passed module.
(For More Information - Please go through the Prospectus).