Wyo. Stat. § 22-13-105: Official marking of paper and absentee ballots.

Before delivering a paper ballot to an elector a judge of election or county clerk shall initial the ballot. No other identifying marks shall be made on an official ballot. An elector shall cast only one (1) ballot or set of ballots at each election. No ballot determined to be valid by the canvassing board shall be rejected solely due to an administrative error of not initialing the ballot.