The production of J/ψ pairs in high energy hadron collisions has been studied by several experiments. Despite the experimental and theoretical efforts, the origin of the process and the relative weight of different production mechanisms still remain unknown. At different center of mass energies the process can be described by single- and double-parton scattering sub-processes and can also be related to the hypothesis of the intrinsic charm of hadrons and the existence of exotic all-charm tetraquark states. Such states were predicted by theory for the first time in 1975 and have recently been experimentally observed.
The COMPASS experiment at CERN uses a 190 GeV/c negative pion beam scattering off different nuclear targets to study dimuon pair production. In this talk, the COMPASS results on J/psi pair production will be presented and compared to theoretical models.