Hi Aspirant!

As your caste certificate of SC category was made in 2017, and of course, it is valid for NEET 2020.
Even it is valid for NEET 2021,22,etc and other competitive exams.
once you made an valid caste certificate then you have no need to create another certificate for SC category student.
for kind information i have made an caste certificate on 2014 and valid in 2018 counslling even today is also valid !