  A study of two-Higgs-doublet models (2HDM) in the decoupling limit reveals
the existence of parameter configurations with a large triple-Higgs
self-coupling as the only low-energy trace of the departure from a Standard
Model (SM) Higgs sector. This observation encourages attempts to search for
double Higgs production at the Large Hadron Collider (LHC) even in mass regions
which have been shown to be very hard to probe in the context of SM-like Higgs
self-couplings. In this document we consider the case of an Intermediate Mass
Higgs (IMH) boson, with 120 GeV <= M_H <= 140 GeV, produced in pairs via
vector-vector fusion, Higgs-strahlung and associate production with
heavy-quarks and decaying into b anti-b pairs. After a detailed
signal-to-background analysis, we confirm that the observation of a Higgs-pair
signal is very challenging in the framework of the SM, even at the LHC with
upgraded luminosity. In contrast, we verify that the sensitivity is sufficient
to detect departures from the SM which would escape detection in the
measurements of the single-Higgs production channels.
