Horses were killed...

I am trying to understand exactly what happened to the horse or horses that were killed in the making of this film.

I've read that two horses were killed, but elsewhere it indicates that the same stunt was shot from two different angles, so that it could be edited in twice, even though it only happened once. I've also seen conflicting accounts of how the horse was killed. Some accounts say that a tilt chute was employed to send the horse off the 70-foot high cliff, and that once in the water, the horse panicked and drowned. However, another account, supposedly from the son of Yakima Canutt, Tap Canutt, who was a colleague of the stunt rider Cliff Lyons, the man who performed the stunt, claims that the horse was simply blinkered and ridden off the cliff. According to this story, the horse landed on a rock and broke its back.

I find it odd that there are so many conflicting accounts of what happened here, and I'm wondering if the matter was ever resolved definitively.