Unfortunately, if he took two torso hits from a .223 he's probably in real bad shape. That round has a reputation for poorly stabilzed bullets that tumble end over end as they pass through body tissue, although some ballistics experts are now questioning that theory. But that issue aside, two upper torso hits from ANY high velocity centerfire rifle with any type round is very bad news for even a large adult male, let alone a 13 year old kid.
Something of an exaggeration, but the truth is nasty enough. They don't "tumble end over end", they "yaw" with the length of the yaw cycle being on the order of 9-15 inches, and that's only for a 1/2 a rotation, at which point they tend to break into two major pieces. A bullet going sideways through you, a fairly long bullet at that, will not exactly make your day. Plus it dumps alot of energy/momentum into the target, resulting in large "stretch" or temporary cavilty, which can also tear up stuff the bullet doesn't even hit directly. Usually it doesn't, but it can, especially if less flexible tissue, like the liver, is struck.