Turntable hardware is bound by a set of manufacturing tolerance stackups (worst case/best case)
setup - no setup is perfect
the pressing itself
In summation of the variance introduced by the above mentioned, it is better to have 2 different turntables, different designs...Do your 'best effort' setup on both. Put a record on one, put the same on the other. Go with whichever sounds better for that record...the latter type of approach makes it simpler (helps cut down the neurosis)
(A legit upgrade in sound quality vs just a difference in sound....confounding difficult thing to discern with turntables setup above a certain point....)
You would end up with a stack of records you'd play with turntable A and a stack of records you'd appreciate better with turntable B.
You could get away with using the same phonostage for both if you bought one that means business....but, everything upstream of it is subject to the summation of above mentioned issues
@newton_john wrote
What is the advantage in having more than one turntable?
Is it not spreading resources thinly when you could buy a better sounding one for the same total spend or upgrade cartridge, phono stage, etc?