Me. Rev. Stat. tit. 18-C, § 3-702

A person to whom general letters are first issued has exclusive authority under the letters until that person's appointment is terminated or modified. If through error general letters are later issued to another, the first appointed representative may recover any property of the estate in the hands of the representative subsequently appointed, but the acts of the latter done in good faith before notice of the first letters are not void for want of validity of appointment.