Yes, I would interview for the job - you may end up going and finding that it just isn't a good fit for you, in which case your problem is solved.
I personally worked retail and hospital at the same time during my P2 year. It was interesting to see both aspects. I ended up quitting the retail job, even though I actually kind of liked it more. I learned a lot at the hospital (though I will respectfully disagree that you will absolutely learn MORE at the hospital), but I was pretty much a glorified delivery person (I was technically an intern but my job duties were those of a technician). My point is, you can learn as much or as little from any job as you would like.
If you've never worked in a hospital (but you do have retail experience), I would be inclined to take the hospital job just so you can see what it is like.
All that said, I would try to see if you can work both places, at least for awhile, and then make your final decision based upon what you like more. In my case, the hospital paid about 25 cents more an hour - definitely not the disparity I often see reported in tech pay - so money wasn't a huge factor.
Edited to add: If you decide to leave your retail job so soon, just be honest with the manager about it. The fact is, pharmacy is a small world and many pharmacists know each other, no matter what practice setting they work in. You ultimately need to do what is best for you and you shouldn't feel guilty about it, but obviously you should try to do it without burning any bridges. Best of luck!
