It's a fine line... From what I've heard from some Realtors answering financing questions on here, I would say it's not the greatest idea to act in dual capacity. There are some Realtors who may be good at both though. I would first get a couple of quotes from others to see if the Realtor/Broker is giving you a fair price.
My personal opinion is that Realtors and Lenders should be separate... It's almost like being the listing agent and buying agent, it's just difficult and should be avoided if possible unless they are family or friend.