  The expected rate for Multiple Parton Interactions (MPI) at the LHC is large.
This requires an estimate of their impact on all measurement foreseen at the
LHC. Conversely it provides new means of studying MPI at the LHC. In this paper
we examine the role of MPI at the LHC, with the design energy of 14 TeV, in - Z
production in association with four jets, - W\pm W\pm in association with zero
or two jets. -W+ W- in association with two jets. In all cases the vector
bosons are assumed to decay leptonically.
  The MPI contribution to Z+4j is dominated by events with two jets with
balancing transverse momentum. It is possible to achieve a good signal to
background ratio, close to 20%, for MPI compared to Single Interaction
processes by selecting events with two jets with large separation in the
transverse plane. The corresponding statistical significance for a luminosity
of 1 inverse fb is about 6.9 for the mu+mu- channel alone.
  The final state channel in which only two same-sign high transverse momentum
charged leptons are required and additional hard jets are vetoed is dominated
by MPI, with an expected yield of 2500 events with the full LHC luminosity.
