Yep. Decapping pins break. Fortunately, they're all the same size. You can take one out of another die in a pinch.
"...RCBS sends a 1/2 dozen..." That's the number in the package. Long before there was an Internet, I busted one and didn't have another set of dies at the time. Sent a letter to RCBS asking where I could get 'em(didn't occur to me to go to my local shop. Very new, so I was). Took about 2 weeks for the package of 6 to arrive in the mail, along with where to get 'em. No questions asked.