  The goal of this paper is to construct distinct trisections of the same genus
on a fixed 4-manifold. For every $k \geq 2$, we construct $2^{k}-1$
non-diffeomorphic $(3k,k)$-trisections on infinitely many 4-manifolds. Here,
the manifolds are spun Seifert fiber spaces and the trisections come from
Meier's spun trisections. The technique used to distinguish the trisections
parallels an established technique for distinguishing Heegaard splittings. In
particular, we show that the Nielsen classes of the generators of the
fundamental group, obtained from spines of the 4-dimensional 1-handlebodies of
the trisection, are isotopy invariants of the trisection. If we additionally
consider the action of the automorphism group on the Nielsen classes, we obtain
diffeomorphism invariants of trisections.
