  A generalized Kerr-Schild ansatz for bigravity, already considered in the
literature, which leads to linear interactions between the metrics is used to
study the bigravity equations in the context of the double copy. By contracting
the resulting spin-2 field bigravity equations of motion using Killing vector
fields, as is usually carried out in general relativity, we arrive to the
single and zeroth copy equations for the mentioned ansatz. For the case of
stationary solutions, we obtain two Maxwell and two conformally coupled scalar
field equations for the single and zeroth copies respectively, and the linear
interactions are absent. In the time-dependent case we obtain equations for the
fields which are coupled. By decoupling these equations and at the zeroth copy
level, we recover a massless and a massive field whose mass is proportional to
the Fierz-Pauli mass and depends on the coefficients of the interaction
potential between the metrics. This has been also previously documented in the
literature and is now reinterpreted within the context of the double copy
proposal.
