  The different forms of the Hamiltonian formulations of linearized General
Relativity/spin-two theories are discussed in order to show their similarities
and differences. It is demonstrated that in the linear model, non-covariant
modifications to the initial covariant Lagrangian (similar to those
modifications used in full gravity) are in fact unnecessary. The Hamiltonians
and the constraints are different in these two formulations but the structure
of the constraint algebra and the gauge invariance derived from it are the
same. It is shown that these equivalent Hamiltonian formulations are related to
each other by a canonical transformation which is explicitly given. The
relevance of these results to the full theory of General Relativity is briefly
discussed.
