http://www.legislation.gov.uk/id/asp/2020/2

SCHEDULE 1Further provision about voting in the referendum

PART 3Postal voting: issue and receipt of ballot papers

Refusal to issue postal ballot paper

23

Where a counting officer is satisfied that two or more entries in the postal voters list, or the proxy postal voters list or in each of those lists relate to the same voter, the counting officer may not issue more than one ballot paper in respect of that voter.