After looking at that graphic, I also think it is confusing. I'll change it to indicate this:
Most early sixes and the 2002 ti/tii/Turbo used the calipers on the right. To accomodate vented rotors, ATE simply added spacers to that same caliper to move the halves apart. Thus the calipers on the 2002 Turbo and some early sixes had vented rotor systems based on the same calipers/caliper spacers.
As far as I know, the caliper on the left never occured on BMWs without the spacer and didn't appear until 1976 (?).
I hope somoone has an explanation for those casting marks. Since those are ATE's numbers, we may never know.