The mystery vessel is certainly not SHIN AITOKU MARU, as that vessel was built as a tanker, and continues to be a tanker. Apart from that, there are too many other differences, such as hull shape, superstructure, and number of sails for it to be the same vessel.
The mystery bulker/gen. cargo vessel does have one feature to note specifically. The extended lattice mast is very similar to the one installed on USUKI PIONEER, indicating, perhaps, that this vessel came out of the same yard. The best bet is she is one of the 14 additional unidentified vessels equipped with those sails apart from SHIN AITOKU MARU, USUKI PIONEER, and AQUA CITY mentioned in some sources.
Regards,
Kyle