Many universities have rules stating that once a piece of work has been submitted for a qualification, it cannot be re-submitted for the award of another qualification.
The MBA is a very prestigious qualification and I doubt very much that anywhere awarding one will give much of an exemption for having a masters, even in a similar subject.
No harm in asking if there is any chance of exempting you from some of the work, I suppose. But like I said in response to one of your other questions, if you want the MBA qualification you will have to put the work in!