Let me put it that way... it depends. I personally tend to look down a bit on dual degree as compared to someone who first got PharmD, worked for a while and then got an MBA. It may be beneficial if you want a) extra letters after your name, b) basic understanding of business, c) you have actually been in the real world and you know exactly why you want an MBA, what concentration, etc. In the last case, dual degree is the best option because it is cheaper and faster. However, if you haven't been out in the real world, you will not get all the benefit of the MBA program - which is why best MBA programs do not accept applicants with less than 3 years of work experience. Another big part of the MBA program is networking - it is not just what you know, it's who you know. In a dual degree, you will be missing out on that aspect. I always feel like that's a soft option - but I am only one person (though others in my department - Business Analytics - tend to think along the same lines).
Just having an MBA will not provide you with a competitive advantage if you do not have skills to back it up - which is why I got the job I have over many other candidates, many of whom had an MBA (I do not, though I plan on getting one when I feel I can really get the most out of the program).
Maybe an MBA would be useful if you want to own and operate your own pharmacy... or for personal enrichment, it makes for a better professional electives set than gerontology. It will certainly help you all other factors being equal. It is just not an instant recipe for success. 🙂