You paid the court fine but HM Court Service sent you a cheque
Bank the cheque. Its yours to keep. If you get trouble then bring an action for breach of paragraph 6(3) of Schedule 12 of the Tribunals Courts and Enforcement Act 2007.
When you have paid a court fine at court after bailiffs have been instructed, it is the practice of some magistrates' court administrators to send you a cheque and say the "warrant is still live".
The law says once you have paid the fine you are "adjudged to pay", the warrant no longer has effect because the sum due on the (genuine) warrant of control is now NIL.
Section 76 of the Magistrates Courts Act 1980 states;
Enforcement of sums adjudged to be paid.
(1)Subject to the following provisions of this Part of this Act, and to section 132 below F1, where default is made in paying a sum adjudged to be paid by a conviction or order of a magistrates’ court, the court may issue a warrant of distress for the purpose of levying the sum or issue a warrant committing the defaulter to prison.
Paragraph 6(3) of Schedule 12 of the Tribunals Courts and Enforcement Act 2007
(3)The property in all goods ceases to be bound when any of these happens—
(a)the amount outstanding is paid, out of the proceeds of sale or otherwise;
(b)the instrument under which the power is exercisable ceases to have effect;
(c)the power ceases to be exercisable for any other reason.
This is why bailiff companies often use forged warrants.
There is nothing in rules of court that enables warrants and court fines to be revived once the enforcement power has been extinguished.
If you are visited by bailiffs about a court fine that you have already paid, then that amounts to an enforcement step and you can start proceedings under paragraph 66 of Schedule 12 of the Tribunals Courts and Enforcement Act 2007, which states;
66(1)This paragraph applies where an enforcement agent—
(a)breaches a provision of this Schedule, or
(b)acts under an enforcement power under a writ, warrant, liability order or other instrument that is defective.
(2)The breach or defect does not make the enforcement agent, or a person he is acting for, a trespasser.
(3)But the debtor may bring proceedings under this paragraph.
(4)Subject to rules of court, the proceedings may be brought—
(a)in the High Court, in relation to an enforcement power under a writ of the High Court;
(b)in a county court, in relation to an enforcement power under a warrant issued by a county court;
(c)in any other case, in the High Court or a county court.
(5)In the proceedings the court may—
(a)order goods to be returned to the debtor;
(b)order the enforcement agent or a related party to pay damages in respect of loss suffered by the debtor as a result of the breach or of anything done under the defective instrument.
Here is how to bring the claim: