What I think is, the reason for asking number of attempts is because they might have a bar on the number of attempts a person might give for the examination. 

And secondly, the reason for entering Hall Ticket number is, so that some of the data about the candidat may be directly taken from the data which is stored in the server, since the same data was filled previously. And the reason also might be to check how many times the person has attempted the exam, for Real.