First, I drew a cuboid 1 and rotated it to get a cuboid 2. There was no problem in this process. I put cuboid 1 and cuboid 2 into 'structure group' to form s1.
In order to compare the behavior of s1 next, I copied s1 to get s2.
Take first axis : z and rotation1: 180 for the whole s2. This doesn't rotate 180 degrees around the z axis. I don't know how to solve this problem.