Curtis:
Yes, it is better for the organization of the plot (and formulation of a logline) that the protagonist have one objective goal. (It's not just better, it's been the rule in Western drama going back to Aristotle's "Poetics".) All other goals should be subordinate to that overarching goal -- steps along the way.
If the antagonist in both his and her abuse is the same villain, then the ONE objective goal would be to bring him to justice for both crimes. If it's a case of 2 separate (and not directly or causally related) antagonists and crimes, then you've got 2 separate stories and objective goals.
BUT: the crime done to him is obviously the source of his subjective problem -- the psychic wounds that need to be healed. And perhaps at the start of the story, those wounds have him in the grips of a death wish. Then -- the inciting incident -- he finds out about his sister's dire situation. Now, he has a reason to live: to rescue his sister. That becomes his objective goal.
Can he bring his own abuser to justice as a collateral consequence of rescuing his sister, a karmic bonus? Maybe, depending on how the plot is constructed. And if he feels he must do so for some peace of mind -- to tame the furies inflicted upon him by his own abuse.
But for the scenario I have sketched, it seems to me, that saving the sister has to be the objective goal. After all, his predicament cursed him with a death wish. Her predicament gave him the will to go on living.
Gave = gift. In a sense, he owes her his life. (And if in the backstory, she tried to rescue him from his own abuse, maybe did something that saved his life -- that's a plot plus: he literally owes her.)
Differentiating and working out the relationship between the objective goal and the subjective need is, imho, one of the greatest challenges in fiction writing. Hope I have clarified more than confused. If any of my off-the cuff babbling actually reflects the story you are trying to tell, then I think you have the raw material for a compelling drama. Best wishes.