Using one agent for both transactions means a single person is tracking both timelines, rather than two agents on separate deals who may not know how a delay on one side, costing $800 to $1,500 in extra legal work if a closing date has to move, affects the other.
Your lawyer's role is distinct from your agent's: the lawyer registers title through Information Services Corporation, disburses your mortgage payout and proceeds, and ensures both closings actually complete on the dates your agent negotiated.
Coordinating both sides from the start is usually simpler than trying to sync two separate deals after the fact. Get your hand-reviewed valuation from Joel Dyck.