Hey Sejal !
No, once you take admission in Aakash with a set of documents, you can't exchange them with any other possible set, be it for the betterment or not of your own.
So, if you have given your Bihar Board marksheet for availing the scholarship, now you won't be able to exchange it with the CBSE one.
And you don't need to worry, this issue won't hamper you at all. Aakash keeps the copy of the document just for the scholarship purpose, there is no issue to be worried once you get the scholarship.
They won't look back or check upon to see any other documents and it won't harm your career in any way.
But make sure, from next time you provide with the single document.

Hope this helps.

Good Luck !