Is cascade refrigeration system the same as two-stage compressor refrigeration system in principle?

It's different. First, two refrigerants overlap, and two-stage compression is two-stage compression of one refrigerant; Cascade system: the high-temperature stage and the low-temperature stage each have a circulation system, and the evaporator of the high-temperature stage serves as the condenser of the low-temperature stage system. Two-stage compression means that the same refrigerant is cooled after the first stage compression, and then enters the second stage compressor for compression. It is divided into intermediate complete cooling and intermediate incomplete cooling. The cascade system will reach a lower temperature than the two-stage system.