  Observations of galaxy cluster mergers provide insights on the particle
acceleration and heating mechanisms taking place within the intracluster
medium. Mergers form shocks that propagate through the plasma, which result in
shock/cold fronts in the X-ray, and radio halos and/or relics in the radio
regime. The connection between these tracers and the mechanisms driving
non-thermal processes, such as inverse Compton, are not well understood. ZWCL
1856.8 is one of the few known double radio relic systems that originate from
nearly head-on collisions observed close to the plane of the sky. For the first
time, we study NuSTAR and Chandra observations of such a system that contains
both relics within their field of view. The spectro-imaging analyses results of
the system suggest weak shock fronts with $\mathcal{M}$ numbers within
2$\sigma$ of the radio derived values, and provide evidence of inverse Compton
emission at both relic sites. Our findings have great uncertainties due to the
shallow exposure times available. Deeper NuSTAR and Chandra data are crucial
for studying the connection of the radio and X-ray emission features and for
constraining the thermal vs. non-thermal emission contributions in this system.
We also present methods and approaches on how to investigate X-ray properties
of double relic systems by taking full advantage of the complementary
properties of NuSTAR and Chandra missions.
