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Using this SO question we can determine where the collision was. We can then modify our code to be

Using this SO question we can determine where the collision was. We can then modify our code to be

void OnCollisionEnter2D(Collision2D col) {
    transform relativePosition = transform.InverseTransformPoint(collision.contacts);
    if (abs(relativePosition.x) > abs(relativePosition.y))
        testing.speedX = 0;
    else
        testing.speedY = 0;
}

void OnCollisionExit2D(Collision2D col) {
    testing.speedY = 10F;
    testing.speedX = 10F;
}

void OnCollisionEnter2D(Collision2D col) {
    var relativePosition = transform.InverseTransformPoint(col.contacts);
    if (abs(relativePosition.position.x) > abs(relativePosition.position.y))
        testing.speedX = 0;
    else
        testing.speedY = 0;
}

void OnCollisionExit2D(Collision2D col) {
    testing.speedY = 10F;
    testing.speedX = 10F;
}

###Edit 2

Using this SO question we can determine where the collision was. We can then modify our code to be

void OnCollisionEnter2D(Collision2D col) {
    transform relativePosition = transform.InverseTransformPoint(collision.contacts);
    if (abs(relativePosition.x) > abs(relativePosition.y))
        testing.speedX = 0;
    else
        testing.speedY = 0;
}

void OnCollisionExit2D(Collision2D col) {
    testing.speedY = 10F;
    testing.speedX = 10F;
}