Yea I wondered since one is rimmed and one is not. I discovered that by leaving the retainer a little loose it allows the case freedom to ride in the shell plate and helps it line up with the mandrel. I still have to watch it and give it a hand once in awhile, but got through 150 rounds yesterday without crushing any more cases.
If your using the 19S shellplate, it is designed for 9mm and 40. So letting it float is the right thing to do.