SHARETuvalu, ELECTORAL PROVISIONS (PARLIAMENT) ACT (2008, last amended in 2014), accessed 21 August 2019
Article 21(1)(d): The elector shall on receiving the ballot paper […] secretly record his vote —
(i) if the election is for the return of one member in respect of the electoral district in which that elector is registered by making a mark or marks on the ballot paper from which his choice of candidate can be deduced;
(ii) if the election is for the return of two members in respect of the electoral district in which that elector is registered by making a mark or marks on the ballot paper from which his choice of candidates (or candidate, if he wishes to record a vote for only one candidate) can be deduced.
NOTE: As can be seen in Schedule 1, there are seven bi-member constituencies and one single member constituency.