Hii aspirant..

In the West Bengal joint entrance examination if any seat is alloted to you in the three consecutive round of counselling then also you are eligible for mop up round.

The mop up round is usually used by the colleges to fill the vacant seats as many times the seat are remaining vacant after the 3 round of counselling 10 the board decrement in the the the opening and closing rank for filling the remaining seats in the colleges.

All the both private and government colleges participate in the mop up round butts usually it is more useful for government colleges as it is used to fill the remaining seats.

Even if you have been allotted a seat through any round of counselling you are eligible to participate in the mop up round and go for a more  preferred college.

Hope it helps. 

Best of luck.