i am a firm believe that this defect is caused by inter breeding by breeding 2 closely related adults
lets face it when most people buy rays they buy them in pairs and in most cases from the same breeder
breeders with lots of pairs of rays don't seam to have this problem as their gene pool is more clean
i still think SOME not all batman rays you see for sale are cut to look that way as the price tag of this type of ray is high lets face it in Asia they cut and dye fish all the time so what would they do for a high priced fish like a batman ray
don't get me wrong this does happen but not always as neat and tidy as the rays pictured in some cases its just a split front lip
a ray like this probably never happens in the wild due to the massive gene pool
if it did happen in the wild the ray would have big problems surviving as rays use suction to pin down their pray a batman ray would have problems doing this