Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 43, § 10

The question of the adoption of not more than one plan may be submitted at an election. If, pending the determination of the question proposed by petition already filed, another petition presenting the question of the adoption of a different plan shall be presented for filing with the city clerk, no action shall be taken upon the later petition, except to file it, until after the submission to a vote of the question proposed by the earlier petition. Should the result of such vote be adverse thereto, proceedings shall then be had upon the later petition as though it had been filed upon the day when such vote on the earlier petition was cast.

If, pending the determination of the question proposed by a petition already filed under chapter fifty-four A, a petition presenting the question of the adoption of one of the plans provided for in this chapter shall be presented for filing with the city clerk, no action shall be taken upon the later petition, except to file it, until after the submission to a vote of the question proposed by the petition under said chapter fifty-four A. Should the result of such vote be adverse thereto, proceedings shall then be had upon the later petition as though it had been filed upon the day when such vote on the petition under said chapter fifty-four A was cast.