  In this paper we consider double parton distribution functions (dPDFs) which
are the main non perturbative ingredients appearing in the double parton
scattering cross section formula in hadronic collisions. By using recent
calculation of dPDFs by means of constituent quark models within the so called
Light-Front approach, we investigate the role of relativistic effects on dPDFs.
We find, in particular, that the so called Melosh operators, which allow to
properly convert the LF spin into the canonical one and incorporate a proper
treatment of boosts, produce sizeable effects on dPDFs. We discuss specific
partonic correlations induced by these operators in transverse plane which are
relevant to the proton structure and study under which conditions these results
are stable against variations in the choice of the proton wave function.
