Let's take a little excursion off the beaten path this time.  In fact, it will be more like ducking under the roped off barrier and wandering in the off-limits area where we aren't necessarily supposed to go, only to find something very interesting. 

The “duet” box is a lovely puzzle composed of two interdependent cubes which are fused together, and which require one another for each to open and reveal their individual secret compartments.