Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 79, § 7G

A person who receives a payment in accordance with section seven B, or who withdraws an amount deposited in accordance with section seven D, may accept the same without prejudice to or waiver of any right to claim a larger sum by proceeding before an appropriate tribunal. No interest shall be recovered except upon such amount of damages as shall, upon final adjudication, be in excess of the amount of such payment or amount deposited.

In the event that the amount of such payment or deposit shall prove to be in excess of damages subsequently assessed by an appropriate tribunal, the petitioner shall be ordered by a proper decree to refund to the body politic or corporate an amount equal to the difference between the amount of such payment or deposit and the damages subsequently assessed, plus costs and interest at the rate of six per cent per annum from the date as of which damages were assessed.

In the event that a payment is made to a person not entitled thereto, the body politic or corporate may recover the same from such person in an action at law or by bill in equity, and the board of officers, upon recovery of such payment, shall dispose of the same in accordance with section seven B or section seven D, as said board of officers shall determine.