If your map has a sky or weather file, make sure there's none of those files ending in _0 or _1 as well. Sometimes it's not just the particles, but other files that can duplicate themselves when exporting.
As for your map, it's going to create the duplicate particles every time you export, but once you delete them, they won't spring back up until you export the map again. I'd hold off on exporting the map until you're totally done with it, then you'll only have to delete the duplicate particles once and be done with it.