It’s dependent upon the firmware in use.
The original Unity firmware is the only one that has ever used combined battery amps for input. It also has both motors on the same ID/config.
Fw5+ (the introduction of UNITY & stormcore support) brought them back into the standard, which is input for battery amps per ESC/side. All VESC firmware since the dawn of time has run with ESC current set per side, given the hardware architecture it started with.
on BB