IT IS MANDATORY TO APPEAR IN BOTH SLOT EXAM.
hello aspirant...
hope you are doing great...
your question is very difficult to answer. you asked it it is mandatory to appear in both slots of the exam. but you did not mention any specific name for the exam about which you wanted to know. by looking into your student profile, you are an Arts aspirant and there are numerous exams for the arts in India. so...kindly mention the name of the exam so that you can get the most accurate answer.
hope this information helps you...
all the best.