  We consider a scenario where the dark sector includes two Feebly Interacting
Massive Particles (FIMPs), with couplings to the Standard Model particles that
allow their production in the Early Universe via thermal freeze-in. These
couplings generically lead to the decay of the heavier dark matter component
into the lighter, possibly leading to observable signals of the otherwise
elusive FIMPs. Concretely, we argue that the loop induced decay
$\psi_2\rightarrow\psi_1\gamma$ for fermionic FIMPs, or
$\phi_2\rightarrow\phi_1\gamma\gamma$ for scalar FIMPs, could have detectable
rates for model parameters compatible with the observed dark matter abundance.
