I would argue there's no need to double pin a cam unless you're running a solid roller with crazy spring pressures and crazy lift, ramp rates, etc. Even then, it would take a lot to convince me its necessary. If you need two dowels to keep your cam gear fromspinning on the cam, you have much bigger problems!
Herb - seriously.....somebody looked at the pile of shrapnel and determined it was a sheared cam dowel that caused it? 
If you have big parts flying around punching holes in the block, there's about a 100% chance that one of them will contact the cam, which would THEN shear the dowel. Much higher chance that the sheared dowel was one of the many results...not the cause.
Except for the sheared dowel the cam suffered no damage, at least no significant damage like you'd see if it was hit by some large parts. I talked to Comp Cams about it and they said that it's not all that uncommon. They also added that they will add the second pin when when you order a cam and timing set (for a price). However, as you note, it's really not possible to tell for certain. I took a bunch of pictures of the carnage. When it blew it was a just past 6,000 rpm in third gear - rev limiter was set at 6,300. Made for a very exciting ride.
