RA4100 Redundancy

We have an RA4100 with dual RA4000 controllers that, a long time ago, was
set up for redundancy. What I want to do is remove this redundancy, so that
the second RA4000 controller in the unit operates as a separate path to the
same logical drives.

What piece of software/hardware controls whether this second controller is
in "redundant mode" or "additional path" mode?

Thanks in advance.