C# Comparing an array insinde a List<int[]>

I have a class called BOX that has a List of ints as the corner point. So each int array holds 2 points an x and y, 1 array for each corner of a box. Next I have a list that stores each box, at this point I want to compare all the points of each box from each list of class BOX. If a match is made I want to make sure that the matching box is not checked again.

class BOX {

    bool matched = false;

    int[] points1 = { 1, 2 };
    int[] points2 = { 1, 3 };
    int[] points3 = { 2, 3 };
    int[] points4 = { 2, 2 };

    public List<int[]> boxPoints = new List<int[]>() { points1, points2, points3, points4 };

void Main() {

    List<BOX> newBoxes = new List<BOX>();
    List<BOX> oldBoxes = new List<BOX>();

        int matchedPoints;

        foreach (BOX boxes in oldBoxes)
        //Something here, but I'm not sure what...

You could put another value in the same array say like a value of 0 to check or 1 don't check or make a new array that coordinates to your 4 points and scan that for a 0 or 1... hope that makes sense.