I do not think the white mottling on the belly can be used to distinguish between juvenile Brown Snake-Eagle and juvenile Black-chested Snake-Eagle. According to Roberts MM a juvenile Black-chested in second-year plumage has a belly mottled with brown and white and at this stage its overall colour is more greyish brown….not as rufous anymore. As JoelR mentioned, the juvenile Brown Snake-Eagle can also have a mottled belly.
Roberts mentions that the juvenile Brown Snake-Eagle sometimes has white streaks on the crown….if I look at the last photos posted, there are some white on the crown but am not sure if this will qualify as “streaks”
I’m agreeing with JoelR’s ID of juvenile Brown Snake-Eagle but for the following reason…..and considering that I’m still trying to learn, I’m will gladly accept any critique on this point.
The tail of the juvenile Black-chested is mostly white with faint black barring…the Brown Snake-Eagle on the other hand has narrow white barring with the tail mostly appearing dark. If I look at Sawubona’s photos the barring more resembles that of a Brown Snake-Eagle than a Black-chested Snake-Eagle…well for me at least.