I don't know if it's common in pharmacy school but, in general, the only time I've seen this happen is if you have something amazing to offer the school. They only steal you if you're worth it, ie: they see your work in the school eventually bringing them more recognition or money. I know we all worked hard in our classes to be competitive, but those kind of people are extremely rare.
In fact, I wouldn't even mention it in my interview if I got into a school already. It might end up backfiring and leaves the impression that you are not serious about their school (having applied to another school). I view it in the way I view job interviews. You wouldn't go into a job interview and mention that you're interested in another company/have been offered a job at another company, would you? No, you only mention it as leverage during salary negotiations when they actually offer you the job. At least that's what I would do.