I have twins..........this is weird!
There was a set of triplets at my university that was similar. Now, I'm absolutely the worst at figuring out identical multiples, unless they really make an effort. Even though I know the info (one wears her hair short, the other has it long, etc), for some reason I can't ever remember which one does which. But I'm bad with names anyway, not a surprise that identical twins etc do that to me.
But the triplets made it extra difficult. Math majors, Softball players, all same classes, mealtimes, dorm, etc etc etc. They did not dress alike (at least by college, don't know about before), but if you just saw ONE the only way of knowing who was who was by the bangs. This was the late 80s, early 90s, and one had flat bangs, one had kind of sticking up bangs, the other had poofy bangs.
...I just don't "get" the whole facebook phenomenon. I mean its fine if that's what you want to do, but I just don't get the whole throw away all phone communication and just communicate via facebook, which is kind of like just having a website and only communicating via your website. Not that there's anything wrong with that.

Its just not for me at all.
To me from what I've observed from others using it, looks like it just creates all kinds of new problems for friends and couples. Husband to wife, "who is Joe Blow and why is he posting about had a great time last weekend" Or "why is my friend ignoring me" or just all kinds of other things I see, and I just say to myself, well that's why I don't use it, plus I just don't have the time to do it.
Of course you don't get it; you don't use it.
Before FB, I communicated with people mainly by email. Before email, I wrote long letters. Phones were for use in high school. Once people get lives and husbands and children, a phone call can be intrusive, and there's always a time limit on one side b/c a husband comes home, etc. With letters, email, FB, there's no time limit that anyone notices. Communication with my friends and extended family is at a level it was never at before.
Sure, there can be problems in marriages. Sometimes I find out thoughts and feelings that hubby has by reading his FB page, and it bugs me (though I'm glad to find out the thoughts and feelings), but he's bad at communicating in those ways anyway! (almost put "IRL" ha ha) FB didn't create that problem. And at least I can read his page; if he kept a journal for those (usually schmoopy and sweet) feelings, I wouldn't snoop in there, so I'd never know!