Hi Alka,

When you fill a form for Banaras Hindu University ( BHU), first of all you have to register yourself there. Then on specific dates you have to apply for various courses. Suppose if you want to register for BSc course, select BSc and register, then select the subject you want to do BSc, and pay the requisite amount, once the payment is done, If you want to register for more subjects go back and select the other subjects. 

So in BHU you can fill as many applications you want.

Hopefully this helps.