Hello aspirant,

What you thought is true. It's better to concentrate on one thing rather than going on with two options. If you concentrate only on JEE Mains then more likely you have good chances to score well in JEE Mains exam. If you concentrate on two exams then it effects your result. You won't be getting enough time to prepare for both the exams and you might end up not getting good score in both the exams. As your aim is to get Computer Science Engineering in NIT/NSIT so JEE Mains is enough for that and concentrate more on JEE Mains.

Hope this helps!!