The parliamentary committee scrutinising a bill to amend the law on elections of MPs on Wednesday voted 32-14 with one abstention to have two ballot papers with different numbers - one for constituency MPs and the other for preferred political party, used to calculate party-list seats.
The amendment follows passage last year of a constitutional amendment to restore the two-ballot system for the next general election.
However, parliamentarians were divided - one said constituency candidates and their parties should have the same number on the ballots, while the other said said they should have different numbers.
The committee met on Wednesday to vote on the matter.
Committee chairman Sathit Pitutecha said a majority of 32 voted for two ballots with different numbers, 14 for two ballots with the same number, with one abstention. Mr Sathit said he abstained, as chairman.
He said committee members from Pheu Thai and Move Forward parties had reserved the right to raise their opposition to the decision during the second reading debate of the bill.
He said the committee would on Thursday consider the amendment of the other bill on political parties.
Pheu Thai leader Cholnan Srikaew said he believed the two ballots should have the same number, to avoid confusing voters.
He believed the vote for two ballots with different numbers was pushed through by people who were afraid Pheu Thai would win the general election by a landslide.