Do I have to register again in mop up round if I had already registered for round 1 and 2 in neet 2019 counselling?
No, you do not have to register again, for 'mop up round' if you have already registered for Counselling Round 1 and 2 in NEET 2019.
You will be taken as registered earlier on the portal. All you need is to just open the portal at the time of mop up round. Because it is going to be conducted online.