  Advanced LIGO and Advanced Virgo could observe the first lensed gravitational
wave sources in the coming years, while the future Einstein Telescope could
observe hundreds of lensed events. It is, therefore, crucial to develop
methodologies to distinguish between lensed from unlensed gravitational-wave
observations. A lensed signal not identified as such will lead to biases during
the interpretation of the source. In particular, sources will appear to have
intrinsically higher masses. No robust method currently exists to distinguish
between the magnification bias caused by lensing and intrinsically high-mass
sources. In this work, we show how to recognize lensed and unlensed binary
neutron star systems through the measurement of their tidal effects for highly
magnified sources as a proof-of-principle. The proposed method could be used to
identify lensed binary neutron stars, which are the chief candidate for lensing
cosmography studies. We apply our method on GW190425, finding no evidence in
favor of lensing, mainly due to the poor measurement of the event's tidal
effects. However, we expect that future detections with better tidal
measurements can yield better constraints.
