LONDON (Reuters) - Some members of Britain’s Conservative Party have been issued with more than one ballot paper to vote for the party’s next leader, who will also become prime minister, the BBC reported on Saturday.

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Ballot papers have been sent to about 160,000 Conservative Party members across the country, asking them to choose between frontrunner Boris Johnson, a former London mayor and foreign minister, and Jeremy Hunt, the current foreign minister.

Voting is due to close on July 22, with the winner set to be announced a day later.

The BBC said an investigation it had carried out found some party members had received two ballot papers, citing one party insider as estimating that more than 1,000 people could be affected.

It said that in some cases this was because members live and work in different constituencies and may have joined the local Conservative associations in both areas. Other members may have changed their name after marriage.

Party Chairman Brandon Lewis said on Twitter that -- as was the case in a general election -- people would only be able to vote once even if they had been sent more than one ballot paper.

Separately on Saturday, The Times newspaper reported that Johnson is backed by 74% of Conservative Party members with Hunt on 26%, according to a YouGov/Times poll. It said a fortnight ago the last YouGov survey gave almost identical figures.

Both candidates appeared at a campaign event in Nottingham, central England, on Saturday.

Johnson was asked about a Sky News report that said 30 Conservative lawmakers led by finance minister Philip Hammond were plotting to stop a no-deal Brexit in October.

“I’m a great admirer of Phil ... but I sat in the cabinet with him when we were all committed to getting ready for no-deal,” he said.

“To the best of my knowledge the chancellor (finance minister) and every other member of the cabinet is still committed to that policy,” he added.

Johnson has pledged to leave the European Union with or without a deal on Oct. 31 if he becomes prime minister, while Hunt has said he would, if absolutely necessary, go for a no-deal Brexit.

Last Monday a group of pro-EU lawmakers failed in their latest bid to prevent Britain leaving the bloc without an exit deal, after parliament’s speaker did not choose their proposal to be put to a vote.