Section 2. In elections, the person receiving the highest number of votes for an office shall be deemed and declared to be elected to such office; and if two or more are to be elected to the same office, the several persons, to the number to be chosen to such office, receiving the highest number of votes, shall be deemed and declared to be elected; but persons receiving the same number of votes shall not be deemed to be elected if thereby a greater number would be elected than are to be chosen. Except as otherwise provided, this section shall apply to all nominations and elections by ballot at primaries or caucuses. Nothing herein shall derogate from the provisions of chapter fifty-four A.