The A4 is syncing the OT and also transmits the prgch-message.
The OT is sequencing the Blofeld but does not transmit prgch (as pointed out in the midi-menu)
For a reason i cannot explain, the OT transmits the prgch from the A4 direct to the Blofeld although the Blo should not receive any prgch according to the OT menu
I guess this is about the midi channels, where you set the global and individual channels … found that confusing at first, because audio tracks receive and send midi data to their respective channel also.