It is up to you really. There are agents in Md that are licensed in PA as well. And visa versa .
So if you want to have 2 agents you may. Your buying agent in PA would be paid by the list agent you buy from in pa. So you would not have to pay 2 commissions.
Some agents are stronger list agents then they are buyers agents.
Plus a MD agent may not have a good grip on the PA market.