Hey Aalok! Seat allotment in counselling is done on the preference basis your preference list of colleges will be checked from the top and as soon as it finds a college accepting you rank, college will be allotted whether there is better college below it.

If we talk about who will get priority, it depends upon the registration, if you registered first your preference list will be checked first and you will be allotted first. This means as we are arranged serial wise here our registrations are arranged serial wise. Hope this may help you.