  Fully accounting for non-dipole effects in the electron dynamics, double
ionization is studied for He driven by a near-infrared laser field and for Xe
driven by a mid-infrared laser field. Using a three-dimensional semiclassical
model, the average sum of the electron momenta along the propagation direction
of the laser field is computed. This sum is found to be an order of magnitude
larger than twice the average electron momentum along the propagation direction
of the laser field in single ionization. Moreover, the average sum of the
electron momenta in double ionization is found to be maximum at intensities
smaller than the intensities satisfying previously predicted criteria for the
onset of magnetic field effects. It is shown that strong recollisions are the
reason for this unexpectedly large value of the sum of the momenta along the
direction of the magnetic component of the Lorentz force.
