9/20/68 has Pigpen and Bobby. I don't have 10/20/68, but if they played Schoolgirl, I am presuming that its with Pigpen, right? BTW, 10/20 looks more like 60 minutes than 90 based on the timings I have from Gordon.
As far as we can tell from the tapes in circulation from between these two dates, the Dead shows (of which just 10/12 and 10/13 circulate) are without Pigpen but with Bobby, and the Matrix "Hartbeats" shows are without Bobby and Pigpen. This could be figured out better if we had more shows to listen too... Dave S..