Oregon Revised Statutes Probate Law § 114.415

(1) When two or more persons are appointed copersonal representatives, the concurrence of all is required for all acts connected with the administration and distribution of the estate, except:

(2) Persons dealing with a copersonal representative who are actually unaware that another has been appointed to serve with the person are as fully protected as if the person with whom they dealt had been the sole personal representative.