Just a warning, I'm not sure if it's like this at all Wal-Marts, but I went in to get the 2X15lb packs of Kingsford at my local store, I had to walk past three HUGE pallets of individual 16.5lb bags right in the entryway with lots of tags that read, "Everyday LOW price - $7.99"
As Danny said, these double-packs are found back in the garden section...