ca final or inter?? whatever the case may be...see you have time for preparing both the group's if you are appearing in Ca Final also in May 2018 provided you have planned your leave and other commitments properly.
the only thing in my opinion that should be considered in decieding whether one or both group is whether you will be able to manage all 8 papers during exams . If you think 16 days you will be able to properly manage all subjects along with revision n all then you can surely go for both groups if deciding it today. Don't waste time and decide whatever you want to