Dear Adivitya,

Actually it depends upon college to college but mostly place seats are left in the top branch also after the first  round of counselling just because they want the student on that seat who really need it. After the first round many students leave their seat and participate in other round or take off from the counselling. This may the golden chance for you so you can participate in further round and grab that seat.

You don't need to worry about because every counselling has done in minimum 4-5 round or it maybe extended, so there is more chance that you will get your preferred seat in you preferred college but you need to very quick and active for that.

Best Of Luck!!!