Sometimes a player will declare several charges at once, often aimed at the same or adjacent enemy units. In such a case the chargers must be specific about their target, it is not enough to say, "I'll charge those two units over there".
Where there is potential confusion in a series of charges then it is sensible to complete one charge at a time, though the player can decide which order to make his charges in. If an initial charge fails because the enemy flees, because the chargers are forced to flee by missile fire, or for whatever reason, then it is possible the first chargers will end their move short of their target, potentially blocking the path of the second charging unit.