Although people like Mike Smith have toyed with this effect in color
I think it is generally more effective in black and white. When everything is reduced to graytones, the combination of similar tones in physically different layers can blend photographically to create ambiguous situations. Basically, the form of the photo assumes the role of content.
Christopher Rauschenberg plays a lot with this in his b/w work
as does Erwitt
but of course the ultimate liner upper has to be Friedlander
All three of these folks were important to my development as a photographer, perhaps to a fault. In fact their influence is so strong that now when I am out shooting I need to make a conscious effort to avoid lining things up or I'll do it unconsciously (more examples here on my website). I suppose this is ok in some ways. What bothers me is that when things in a photo are lined up, the shot can appear too thought out. I think there is a delicate balancing act between casualness and perfection. A good photo requires some of each, yet too much of either can ruin it. So when a shot is very carefully lined, when the elements in the shot interrelate with such precision that any other vantage point would ruin the photo, that photo might be missing a slight piece of its soul, the accidental part. Such photos seem to be more about the photographer than what's in the photo. And yes, all photos are to some extent about the people who take them, but that's even more reason it requires special effort to hide one's self. Lining things up is not hiding onesself.
Realizing this, I've tried to break my lineup habit in a few ways. First, I switched a few years ago from an SLR to a rangefinder camera. While it is possible to line things up using a rangefinder, it is much more difficult than with other cameras. It takes guesswork to compensate for parallax. I can't imagine how Friedlander took all those lineup shots using a Leica. So some of the temptation to line things up is removed. Secondly, I've started shooting color in the past year. As I mentioned above, color seems much less suited to lineups than b/w. Now when I do line things up, the photos usually fail. It's the ones which aren't lined up, the naturally "objective" ones which I find myself liking more and more.