Truth is stranger than friction. So go ahead and soak in this mind blowing story: Strange tale of 2 presidents
Guess you can't say that coincidences don't exist anymore. I wonder how accurate the facts are, perhaps some are false and they're just relying on the fact noone actually knows or would take the time to look it up?
I don't mean to burst any bubbles, but everyone may want to consider what Snopes has to say on the matter: http://www.snopes.com/history/american/lincoln-kennedy.asp