Remember that Atta left a rather detailed trail of his whereabouts before Sept. 11th. He was able to do so because nobody could have imagined what he was intending to do. We are no longer so inattentive.
Surely the scrawny Gerung was not intending to carry out an attack by himself (why take all those weapons if you're acting alone?). Either there were accomplices with reservations on the same flight in order to carry out a hijacking or Gerung was sent out on a test run to see how lax security at O'Hare was. Either way, he's not acting alone.
The FBI *may* be pretending to see no connection in hopes the accomplices will surface, emboldened that we "foolish Americans" have dropped the ball again and that they don't have to hide out until the search dies down.
My other thought is that, unlike liberals who celebrate "diversity", many foreigners wish to stick with their own kind. Therefore, there may be apartments overrun with similarly named foreigners who all find lodging within blocks of each other. I wouldn't put too much emphasis on two foreigners with similar addresses but I wouldn't dismiss the apparent link entirely either.