Did you both took a separated bear or both the same and used the harvest at same time exploit? the animals -always- stay long enough around for me to harvest everything from, thats at least 30 sec but more accurate would be 1 maybe even 2 min before they despawn.
often enough I killed two or three animals that were attacking me ( thus killed them all within a min) and had enough time to loot/ harvest them all and watch thier body's laying about for a while.