An agreement such as this was called a Concord or a Fine. Up to 1195, each party was given a copy of the agreement, but after this date the agreement was written onto one sheet of parchment, one on each side and one at the foot. The copies would then be separated by cutting the parchment along a wavy a line to prevent forgery. The right and left hand copies were given to the parties and the third copy, at the foot of the parchment, was retained by the court.
This is the reason these documents are known as feet of fines.
The copies kept by Vaughan and Nyche are long gone, but court document, the bottom half of this Feet of Fines, has survived, you can see the top edge is wavy where it joined the other two pieces.