yes, you can replace one KPP600-20 with another KPP600-20.... or KSP3x40 by another KSP3x40
as far as i know this is not an issue even if article number is different or internal HW/FW and appearance of the unit are different... at least this was never an issue so far. Newer KSS also don't make a fuss if the replacement is different as long as it is same or higher performance.
for example KSP3x40 (40A version) can be replaced by another KSP3x40 or KSP3x64, but not KSP3x20.
on older KSS that works too but requires modifying WoV project (must match installed hardware)
btw. here is an example of drive packs (KPP/KSP) with different appearance (curved vs flat front):
