The problem is finally solved - I bought a Trust YULA GXT 545 PS3/PC wireless controller with a dedicated dongle (set to D-input, buttons must be manually configured) for "Player 2" and everything works fine in RetroArch 🙂
Now the original PS3 controller (connected first on channel 1) works for "Player 1" and the game menu, and the Trust controller (connected second on channel 2) only works for "Player 2":
text alternatywny
text alternatywny
text alternatywny