  In this paper we will provide smoking-gun signatures of nonlocal interactions
while studying reflection and transmission of waves bouncing through two Dirac
delta potentials. In particular, we will show that the transmission of waves is
less damped compared to the local case, due to the fact that nonlocality
weakens the interaction. As a consequence the echoes are amplified. These
signatures can be potentially detectable in the context of gravitational waves,
where two Dirac delta potentials can mimic the two potential barriers at the
surface and at the photon sphere of an ultra compact object, or, at the two
photon spheres of a wormhole, experiencing nonlocal interactions.
