i have just started my grads in bsc comp. sci. i want to know if i am eligible for the dual graduation course of bsc it and gims by IIHT

Though you can, but personally, I would not like to suggest you. It's like "Jack of all trades, Master of None". Rather stick to one field and prosper in that field. Moreover, both the above mentioned fields are not inter related. So you have to carefully decide exactly which career stream you want