  The large-amplitude longitudinal oscillations of solar filaments have been
observed and explored for more than ten years. Previous studies are mainly
based on the one-dimensional rigid flux tube model with a single magnetic dip.
However, it is noticed that there might be two magnetic dips, and hence two
threads, along one magnetic field line. Following the previous work, we intend
to investigate the kinematics of the filament longitudinal oscillations when
two threads are magnetically connected, which is done by solving
one-dimensional radiative hydrodynamic equations with the numerical code
MPI-AMRVAC. Two different types of perturbations are considered, and the
difference from previous works resulting from the filament thread-thread
interaction is investigated. We find that even with the inclusion of the
thread-thread interaction, the oscillation period is modified weakly, by at
most 20% compared to the traditional pendulum model with one thread. However,
the damping timescale is significantly affected by the thread-thread
interaction. Hence, we should take it into account when applying the consistent
seismology to the filaments where two threads are magnetically connected.
