DualShock 4 via Bluetooth is seen as two controllers under RetroArch

Found this by booting up a GBA game, but I presume it's universal across the RetroArch games library.

Upon launching an emulated game, RetroArch detects two controllers. The first controller is the DualShock 4 as connected via Bluetooth, the second is seen as an Xbox 360 controller as rebound by Steam Input. This is problematic for multiplayer, but moreso it means that rebinding controls for single player games can't be done through Steam Input and HAS to be done by launching RetroArch into RGUI, and fiddling with the Advanced settings if you want a remap to only be per-core.

Preferably you should be able to set a Steam Input profile per core, and have that be the only controller detected by RetroArch.