JJA -- that's John Joseph Adams, listed as the editor -- mostly does reprint anthologies -- finding a whole bunch of already-published stories with a similar theme (which sounds like zombies right now), contacting the authors and asking for permission to reprint.

It's nice for him cause he doesn't have to pay as much (since first print rights are already gone), and nice for the authors cause they get a bit more profit on the story, plus more exposure.

"Some Zombie Contingency Plans" by Kelly Link has already been published at least twice, and "The Skull-Faced Boy" by David Barr Kirtley is also a reprint -- "Bitter Grounds", Neil's story, has also been put in at least two different short story collections.