Restriction when Creating Second Design Case in RF-LAMINATE

No, unfortunately this is not possible.

The layer structure is assigned to certain surfaces in RF‑LAMINATE.

Layer Structure in RF-LAMINATE Assigned to Surface No. 1

The respective surface then obtains the stiffness defined via this layer structure for the determination of internal forces in RFEM.

Dialog Box "Edit Surface" of Surface No. 1 with Stiffness from RF-LAMINATE

If you want to perform a calculation with different layer structures, you have to do it in a copy of the file (another model with a different layer structure).