Yes and no, my Friend...
Only one occurrence to my knowledge, which is the one that inspired this scene (in the Saga of Burnt Njàll, Island c. 1300, chapt. 55). Almost no one can catch (from behind) and return a dart (spear, javelin) in the same motion. But by definition, a hero is a hero : he can do everything better than ordinary mortals. A Saga is a tale, an epic poem...
If we look carefully at the beginning and at the end of the scene, the javelin comes from nowhere and then, it goes to nowhere. We are in front of a green screen and there has been digital editing. Cinema is cinema...
Training has nothing to do with. The exception can not be considered as the rule.
Living history is also not reality, that's a fact. But for me, the approach is good : I read and try to understand, then I make things and experiment them in less or more "realistic" conditions. I do sport and train outdoor (in the mountains). After 15 years, I have a little experience with ancient weapons and their use (for ex. I can make a Balearic sling, use it and hit a static or moving target with a very good ratio).
Training, cold-blood, adrenalin and a good assessment of the situation create good reflexes. Only one serious wound in assault : I know that it is possible to deflect or avoid a javelin if necessary, even if it spins at almost 100 km/h. Ballistics has its laws !
Just like you, but on a different path, my experience means that I don't confuse war with the image of war. This scene is an image of war.
Izan ontsa. Be well...