Wash. Rev. Code § 29A.08.610
The secretary of state shall conduct an ongoing list maintenance program designed to detect persons registered in more than one county or voting in more than one county in an election. This program must be applied uniformly throughout the state and must be nondiscriminatory in its application.
The office of the secretary of state shall search the statewide voter registration list to find registered voters with the same date of birth and similar names. Once the potential duplicate registrations are identified, the secretary of state shall refer the potential duplicate registrations to the appropriate county auditors, who shall compare the signatures on each voter registration record and, after confirming that a duplicate registration exists properly resolve the duplication.
If a voter is suspected of voting in two or more counties in an election, the county auditors in each county shall cooperate without delay to determine the voter's county of residence. The county auditor of the county of residence of the voter suspected of voting in two or more counties shall take action under RCW 29A.84.010 without delay.
RCW 29A.08.610
Effective dates-2004 c 267: See note following RCW 29A.08.010.