That's cool!
In previous studies "The bipaternal mice exhibited developmental disorders, including craniofacial deformities, where their facial width-to-length ratio was broader compared to normal mice" and "difficulty suckling", with only 12% survival rate at birth. Their approach alleviates both those defects, "however, the mice still exhibited behavioral abnormalities, such as a tendency to enter the center of an open-field test, which is contrary to the instinctive behavior of rodents". A previous 2023 japanese study did something similar using skin stemcell and relying more heavily on genome editing.
Two main benefits outlined in this Reuters article going a bit more in depth seem to be around regenerative medicine and potentially a later method "for producing offspring through unisexual reproduction" for endangered species.