If the tank is periodically cleaned, and the recirculation polishing
system KEEPS the tankage clean, then NO I dont personally recommend
nor use filters in parallel.

However and to thwart "Mr. Murphy", to be ready to take care of
extreme emergencies (wearing belt, suspenders, AND velcro) I recommend
use of a small 1-3 gallon 'day tank' downstream of the filter set,
mounted physically 'above' the engine. The tank would be so designed
that it always is full and cannot drain all by itself unless you
'throw a valve' at the bottom; plus a vent valve that opens to
atmosphere. Then, when all hell breaks loose, such as broken lift
pump, clogged filters, etc. and since the oil would already be
filtered, all you have to do is open the bottom drain and atmospheric
vent ..... and would have 1 to 4 hours of fuel available.
Alternatively, and again for a 'clean' system, you can simply install
a 3 valve bypass (no filter in the bypass) around all the filters so
that you can momentarily open the bypass and change the filters. But
for all filters you must have a means to quickly purge any air that
enters during changeout, so install a small (fuel oil compatible)
12vdc fuel pump between the tank and the first filter to 'push' the
oil through the filters to aid in 'air-bleeding'. When not needed
that fuel pump will just 'sit there' and not add any restriction to
flow due to the orientation and design of the poppet check valves. On
large diesel (prime movers) fuel systems they dont bother to 'bleed'
as they have 'air trap knockout pots installed - just an empty filter
housing installed upside down with a vent valve on top ... but this
can only be used in a pressurized system.

SUMMARY
If you dont have a clean tank, dont have an onboard polishing system,
dont have a day tank; then yes, consider to install a parallel
arrangement thats easily 'bleed-able'. Such a system should ALWAYS be
monitored with gages to know WHEN to change AND for best effect should
be run with ALL filters 'on-line' and filtering. I dont think this is
necessary as if you are using gages to monitor the status of the
filters, you can usually see a problem developing long before you need
to change-out --- again, thats in a system with a 'clean' tank. How
to use such gages: run the engine at FULL/max. rpm, then read the
gages. On the Parker.com/Racor website there are (somewhere)
published charts indicating ----- 'gage vacuum' versus how much fuel
is flowing through the filters----- (if using sequential filters -
then the results of both filters are additive with respect to flow
rate), you want to change out the filters when they reach 75-80% of
maximum differential pressure (∆P), 100% ∆P would be the value of
output of your lift pump .... when its 'deadheaded' (the valve at the
tank is OFF, etc.) .... again all values taken with the engine at max.
rpm or wide-open-throttle WOT ... while the engine is 'in gear' and
'under load'.

OTHER
Again, the best bet is only to buy your fuel from a 'high turnover'
source such as a depot that caters to 'watermen', or carry it in from
a high volume truckstop, keep only the amount of fuel in the tank you
NEED plus some 'reserve'. If you MUST buy your fuel from a 'marina',
FIRST pour some of the fuel into a clear glass container, hold it up
between your eyeball and the sun .... and if there is any 'cloudiness'
to fuel .... go somewhere else. If you dont put crap into your tank,
keep your tank clean .... you wont be challenging the filters. Filters
only do the job they were designed to do .... take out crap; if you
dont put crap into the tank and dont let the crap 'grow' (agglomerate)
in your tank, you really dont need filters. Just remember - the
smaller the tank the greater the vulnerability to fouling and fuel
degradation. For longterm boat 'lay-up', I remove ALL the fuel in the
tank - why feed all those fungals and bacteria?

hope this helps.