Hi Kirti

This is my personal opinion that there is certainly no harm in appearing in more than one entrance exams if you think you can study hard to meet the requirements of all.

For engineering, you will have to study Physics, Maths and Chemistry thoroughly for all the exams. The syllabus for all engineering exams will be covering these three subjcets with a variation in topics. However, for medical, you will have to study Physics, Chemistry and Biology. Though, Physics and Chemistry will remain the same for both engineering and medical exams, there may be difference in the pattern, marking scheme and questions of both the exams. Therefore, if you think you can study hard to make it through NEET and JEE, you should appear for both.

All the best ! 

Hi Kirti,

It depends on you. If you want to go for any field either medical and engineering then it's OK to appear for both the exams. The syllabus of above exams varries little bit. If you can manage then it will be a practice for you. But if your field is decided then I will suggest you to focus on any one exam. 

All the best!!