Again, it's possibly feasible. But this technology and these systems are governed by various international bodies. In order for the manufacturers of this technology to even use it on board, they have to pass very rigorous testing. The classification societies that govern the construction of vessels and the equipment that's on board are well aware of this risk. They have enabled very strenuous testing to be sure that what you have on board your vessel cannot be duplicated.
Having said that, if some group or somebody were to dedicate some amount of time and money to trying to create a duplicate system whereby they could trick or possibly pass false information, it's possible.