Possibly real, but not "10 (or even 8) 'ab muscles'"
The appearance of compartmentalized 'ab muscles' is due to an anatomical structure called the abdominal linea alba.
It is common for there to be three 'tendinous intersections' (on each side) which create the classic 'six-pack' appearance -- however, studies of cadavers indicate that, due to genetic variations, four or even five are possible; a different study found again that three was most common, but noted that two or even just one was also possible.
Again, these are genetic variations and having a 10-pack is not indicative of superior physical fitness compared to those mere mortals who can only muster an 8-pack.