Since this is the point we’re trying to reconcile you cannot simply assume it.
There may be other ends, which would be related to the intent, but there can only be one proximate end. (See the last comment in this post).
“Accidental” does not mean “accidental to the act”, it means “accidental to the intent”, that is, unintended.
Yes, one act can have several ends, but one object cannot since it is by definition the sole proximate end.
How does this not prove my point? The movement (act) has a per se terminus (life for the four) and an accidental terminus (death of the one). Given that the “movement” receives its species from the former, and (explicitly) not the latter, the moral species of the act does not flow from the accidental (unintended) consequence.
Now that I have looked up this reference it appears you omitted a rather significant point, which is this:
One and the same act, in so far as it proceeds once from the agent, is ordained to but one proximate end
And there it is. An act is “ordained to but one proximate end.” This confirms what I have been claiming.