I don't think it won't be allowed, but I don't think two pharmacists will really help you at all, except to confirm what the first one said about you. LORs are a nice chance to see another perspective of you from a third-party - I'd want to give as wide a view as possible. So it's nice to have a research professor to talk about your capabilities as a researcher, your professor to talk about your skills as a student, your pharmacist to talk about your potential as a pharmacist. Unless you worked at 2 different pharmacies or performed different tasks under each pharmacist, each pharmacist will say the same about you. It's like, having two different essays, but copying and pasting your first essay for your second essay - it doesn't tell the admissions committee anything new!
My professor strongly discouraged us to do that. I was in a bio-lab class where we have 3 professors teaching us - and the professor told us, it's great to ask one of us for a LOR. However, it's silly to ask two of us for a LOR. We will say approximately the same things about you - you're wasting a LOR.