Thanks for the report, I was able to confirm this. According to Bulbapedia, "If targeting an opponent when there are multiple opponents, Dragon Darts' first strike targets the original target and its second strike targets the other opponent. If either the original target or its ally would take no damage from Dragon Darts, both strikes are directed at the other Pokémon instead. If Dragon Darts targets an ally, both hits will hit that ally.".
Currently, Dragon Darts hits the targeted Pokemon with both hits - not spreading it out, and not changing targets if the targeted Pokemon would take no damage. Note that this also applies for Triple and Horde battles.
Moved to internal.