  We explore the possibility of very heavy dibaryons with three charm quarks
and three beauty quarks, $bbbccc$, using a constituent model which should drive
to the correct solution in the limit of hadrons made of heavy quarks. The
six-body problem is treated rigorously, in particular taking into account the
orbital, color and spin mixed-symmetry components of the wave function. Unlike
a recent claim based on lattice QCD, no bound state is found below the lowest
dissociation threshold.
