what makes cyclists more visible is hi vis jackets and good cycle lights.
there is notning wrong with riding two abreast if the cyclist then moves in to allow cars to overtake when overtaking is sensible,
cycling two abreast is, when there are cars behind, who clearly want to overtake when it is safe to do so, ,is a tactic that is not safe and only winds up car drivers even more, if cylists have the courtesy to move in, car drivers in my experience respond by allowing them more room ,courtesy encourages courtesy in others