Hello, 

If you select a college alloted to you in the 2nd round and you freeze your seat. Then in this case you won't be able to choose the option for the college allotted to you in the first round. 

But in case you haven't freezed your choice in the 2nd round for any college alloted to you. Then, in this case you have to report at the reporting centre to accept the seat alloted and you need to freeze your seat. 

This is how the whole process will work out!!!

I hope this would help you. For further queries please feel free to write me down in the comment box.