Double parton scattering, i.e. two parton hard scattering processes in the
same hadron-hadron collision, may constitute an important background for Higgs
and other new particle searches at the LHC. We point out that like-sign W pair
production provides a relatively clean way of searching for, and calibrating,
double parton scattering at the LHC.Comment: 10 pages, LaTeX, 5 figures, epsfi