When did archers start splitting arrows? Around the 17th century. In fiction, that is: It’s unclear whether splitting an arrow from nock to tip in the manner depicted in Brave and other films and stories is possible at all in real life. Archers do plant arrows in the back of other arrows—it’s a rare but not uncommon occurrence called "telescoping" or shooting a "Robin Hood," that seems to be on par with a hole-in-one in golf—but there’s no evidence that it’s possible to sail one arrow straight through another.
YouTube suggests otherwise. Update from a reader:
Mythbusters covered this a few years ago. Basically, it boils down to the material of construction of the arrow. A wooden arrow won't split tail-to-tip due to the grains of the wood that the second arrow will follow. The did achieve a split with a bamboo arrow though.
The Dish 