  We study the azimuthal modulations of dihadron fragmentation functions
(DiFFs) of a transversely polarised quark using an NJL-jet based model that
incorporates the Collins effect for single hadron emission. The DiFFs are
extracted as Monte Carlo (MC) averages of corresponding multiplicities using
their probabilistic interpretation. To simplify the model and highlight the
possible mechanisms that create this modulation, we choose the elementary
Collins function to be proportional to the elementary unpolarised fragmentation
and a constant probability ($P_{SF}$) for the quark to flip its spin after a
single hadron emission. Moreover, as a leading order calculation, only one of
the produced hadrons in the decay chain of the quark is produced with
elementary Collins modulation. We calculate the dependence of the polarised
DiFFs on various angles such as the azimuthal angle of the single hadron and
the angle of the two hadron production plane $\varphi_R$ for several values of
$P_{SF}$. We observe that the polarised DiFFs for oppositely charged pion pairs
exhibit a $\sin(\varphi_R)$ modulation. This effect is induced purely via the
elementary Collins effect and persists even when the quark completely
depolarises after a single hadron emission ($P_{SF}=0.5$). Moreover, similar
sine modulations are present in the distribution of pion pairs with respect to
the azimuthal angle of their total transverse momentum, $\varphi_T$.
