  The motion of a vortex-(anti)vortex pair is studied numerically in the
framework of a dynamical Ginzburg-Landau model, relevant to the description of
a superconductor or of an idealized bosonic plasma. It is shown that up to a
fine "cyclotron" internal motion, also studied in detail, two vortices brought
together, rotate around each other, while a vortex and an antivortex move in
formation parallel to each other. The velocities of the vortices in both cases
are measured to be in remarkable agreement with recent theoretical predictions,
down to intervortex distances as small as their characteristic diameter.
