9 times out of 10, I never saw the earlier post, and I would guess that 90 Freepers out of 100 never saw it either, so what's the problem?
Unless one sits at the computer for hours on end, reading every post, one will miss things.
If you go away from Free Republic for a couple of hours, the whole front page is gone, replaced by new and (mostly)interesting stuff. Who has time to go to the next page, and so on and so on.
I say three cheers to the double posters, and boo to the net nags who jump in to admonish them.