  In contrast to single-component superconductors, which are described at the
level of Ginzburg-Landau theory by a single parameter \kappa and are divided in
type-I \kappa<1/\sqrt{2} and type-II \kappa>1/\sqrt{2} classes, two-component
systems in general possess three fundamental length scales and have been shown
to possess a separate "type-1.5" superconducting state. In that state, as a
consequence of the extra fundamental length scale, vortices attract one another
at long range but repel at shorter ranges, and therefore should form clusters
in low magnetic fields. In this work we investigate the appearance of type-1.5
superconductivity and the interpretation of the fundamental length scales in
the case of two bands with substantial interband couplings such as intrinsic
Josephson coupling, mixed gradient coupling and density-density interactions.
We show that in the presence of substantial intercomponent interactions of the
above types the system supports type-1.5 superconductivity with fundamental
length scales being associated with the mass of the gauge field and two masses
of normal modes represented by mixed combinations of the density fields.
