  Multiply quantised vortices (MQVs) within single component Bose-Einstein
condensates are unstable and decay rapidly. We show that MQVs can be stabilised
by adding a small number of atoms of a second species to the vortex cores, and
that these atoms remain in the vortex core as the system evolves. A consequence
of the stabilisation is that nearby co-rotating vortices can orbit in the
opposite sense to their individual rotations when enough of the second species
is present. This has implications concerning the imaging of vortices, as well
as quantum turbulence and vortex nucleation in two-component condensates, such
as those involving mixtures of $^{87}$Rb and $^{133}$Cs.
