zero problems when connected just single cable to each Si2169D,
almost all combinations tested
A1+B1 - OK
A2+B2 - OK
A2+B1 - OK
A1+B2 - can't see reason to continue
just one guess,
maybe inside the tuner has been stuck some bridge from previously used Internal Loop-trough
=== Cable_1 Tuner_A2 ===
=== Cable_3 Tuner_B2 ===
OK main tuner A2 19E 10.744 H 1_0_1_7035_41B_1_C00000_0_0_0 PHOENIX
OK PiP tuner B2 19E 10.876 V 1_0_1_7790_424_1_C00000_0_0_0 CALLE 13
OK main tuner A2 19E 10.876 V 1_0_1_7790_424_1_C00000_0_0_0 CALLE 13
OK PiP tuner B2 19E 10.744 H 1_0_1_7035_41B_1_C00000_0_0_0 PHOENIX
OK main tuner A2 19E 10.876 V 1_0_1_7790_424_1_C00000_0_0_0 CALLE 13
OK PiP tuner B2 36E 12.015 V 1_0_19_89F_16_70_1680000_0_0_0 THT HD
OK main tuner A2 19E 10.876 V 1_0_1_7790_424_1_C00000_0_0_0 CALLE 13
OK PiP tuner B2 36E 12.341 H 1_0_16_451_B_70_1680000_0_0_0 CTC
OK main tuner A2 19E 10.744 H 1_0_1_7035_41B_1_C00000_0_0_0 PHOENIX
OK PiP tuner B2 36E 12.015 V 1_0_19_89F_16_70_1680000_0_0_0 THT HD
OK main tuner A2 19E 10.744 H 1_0_1_7035_41B_1_C00000_0_0_0 PHOENIX
OK PiP tuner B2 36E 12.341 H 1_0_16_451_B_70_1680000_0_0_0 CTC
OK main tuner A2 36E 12.015 V 1_0_19_89F_16_70_1680000_0_0_0 THT HD
OK PiP tuner B2 36E 12.341 H 1_0_16_451_B_70_1680000_0_0_0 CTC
OK main tuner A2 36E 12.341 H 1_0_16_451_B_70_1680000_0_0_0 CTC
OK PiP tuner B2 36E 12.015 V 1_0_19_89F_16_70_1680000_0_0_0 THT HD
=== Cable_3 Tuner_A2 ===
=== Cable_1 Tuner_B2 ===
OK main tuner A2 19E 10.744 H 1_0_1_7035_41B_1_C00000_0_0_0 PHOENIX
OK PiP tuner B2 19E 10.876 V 1_0_1_7790_424_1_C00000_0_0_0 CALLE 13
OK main tuner A2 19E 10.876 V 1_0_1_7790_424_1_C00000_0_0_0 CALLE 13
OK PiP tuner B2 19E 10.744 H 1_0_1_7035_41B_1_C00000_0_0_0 PHOENIX
OK main tuner A2 19E 10.876 V 1_0_1_7790_424_1_C00000_0_0_0 CALLE 13
OK PiP tuner B2 36E 12.015 V 1_0_19_89F_16_70_1680000_0_0_0 THT HD
OK main tuner A2 19E 10.876 V 1_0_1_7790_424_1_C00000_0_0_0 CALLE 13
OK PiP tuner B2 36E 12.341 H 1_0_16_451_B_70_1680000_0_0_0 CTC
OK main tuner A2 19E 10.744 H 1_0_1_7035_41B_1_C00000_0_0_0 PHOENIX
OK PiP tuner B2 36E 12.015 V 1_0_19_89F_16_70_1680000_0_0_0 THT HD
OK main tuner A2 19E 10.744 H 1_0_1_7035_41B_1_C00000_0_0_0 PHOENIX
OK PiP tuner B2 36E 12.341 H 1_0_16_451_B_70_1680000_0_0_0 CTC
OK main tuner A2 36E 12.015 V 1_0_19_89F_16_70_1680000_0_0_0 THT HD
OK PiP tuner B2 36E 12.341 H 1_0_16_451_B_70_1680000_0_0_0 CTC
OK main tuner A2 36E 12.341 H 1_0_16_451_B_70_1680000_0_0_0 CTC
OK PiP tuner B2 36E 12.015 V 1_0_19_89F_16_70_1680000_0_0_0 THT HD
=== Cable_1 Tuner_A2 ===
=== Cable_3 Tuner_B1 ===
OK main tuner A2 19E 10.744 H 1_0_1_7035_41B_1_C00000_0_0_0 PHOENIX
OK PiP tuner B1 19E 10.876 V 1_0_1_7790_424_1_C00000_0_0_0 CALLE 13
OK main tuner A2 19E 10.876 V 1_0_1_7790_424_1_C00000_0_0_0 CALLE 13
OK PiP tuner B1 19E 10.744 H 1_0_1_7035_41B_1_C00000_0_0_0 PHOENIX
OK main tuner A2 19E 10.876 V 1_0_1_7790_424_1_C00000_0_0_0 CALLE 13
OK PiP tuner B1 36E 12.015 V 1_0_19_89F_16_70_1680000_0_0_0 THT HD
OK main tuner A2 19E 10.876 V 1_0_1_7790_424_1_C00000_0_0_0 CALLE 13
OK PiP tuner B1 36E 12.341 H 1_0_16_451_B_70_1680000_0_0_0 CTC
OK main tuner A2 19E 10.744 H 1_0_1_7035_41B_1_C00000_0_0_0 PHOENIX
OK PiP tuner B1 36E 12.015 V 1_0_19_89F_16_70_1680000_0_0_0 THT HD
OK main tuner A2 19E 10.744 H 1_0_1_7035_41B_1_C00000_0_0_0 PHOENIX
OK PiP tuner B1 36E 12.341 H 1_0_16_451_B_70_1680000_0_0_0 CTC
OK main tuner A2 36E 12.015 V 1_0_19_89F_16_70_1680000_0_0_0 THT HD
OK PiP tuner B1 36E 12.341 H 1_0_16_451_B_70_1680000_0_0_0 CTC
OK main tuner A2 36E 12.341 H 1_0_16_451_B_70_1680000_0_0_0 CTC
OK PiP tuner B1 36E 12.015 V 1_0_19_89F_16_70_1680000_0_0_0 THT HD
=== Cable_3 Tuner_A2 ===
=== Cable_1 Tuner_B1 ===
OK main tuner A2 19E 10.744 H 1_0_1_7035_41B_1_C00000_0_0_0 PHOENIX
OK PiP tuner B1 19E 10.876 V 1_0_1_7790_424_1_C00000_0_0_0 CALLE 13
OK main tuner A2 19E 10.876 V 1_0_1_7790_424_1_C00000_0_0_0 CALLE 13
OK PiP tuner B1 19E 10.744 H 1_0_1_7035_41B_1_C00000_0_0_0 PHOENIX
OK main tuner A2 19E 10.876 V 1_0_1_7790_424_1_C00000_0_0_0 CALLE 13
OK PiP tuner B1 36E 12.015 V 1_0_19_89F_16_70_1680000_0_0_0 THT HD
OK main tuner A2 19E 10.876 V 1_0_1_7790_424_1_C00000_0_0_0 CALLE 13
OK PiP tuner B1 36E 12.341 H 1_0_16_451_B_70_1680000_0_0_0 CTC
OK main tuner A2 19E 10.744 H 1_0_1_7035_41B_1_C00000_0_0_0 PHOENIX
OK PiP tuner B1 36E 12.015 V 1_0_19_89F_16_70_1680000_0_0_0 THT HD
OK main tuner A2 19E 10.744 H 1_0_1_7035_41B_1_C00000_0_0_0 PHOENIX
OK PiP tuner B1 36E 12.341 H 1_0_16_451_B_70_1680000_0_0_0 CTC
OK main tuner A2 36E 12.015 V 1_0_19_89F_16_70_1680000_0_0_0 THT HD
OK PiP tuner B1 36E 12.341 H 1_0_16_451_B_70_1680000_0_0_0 CTC
OK main tuner A2 36E 12.341 H 1_0_16_451_B_70_1680000_0_0_0 CTC
OK PiP tuner B1 36E 12.015 V 1_0_19_89F_16_70_1680000_0_0_0 THT HD