In the Parallel section of the manual, it just says to refer to the single unit PV connection instructions. Nothing indicates that special consideration is required for the PV inputs when in parallel mode.
Each unit has its own MPPT controller, which would drive charging of the battery bus with whatever solar input it gets. Just like you can connect 2 independent solar chargers to one battery bus, you can also connect the two independent SPF3000 units to the same bus and have each one charging independently from it's own PV input.
