Short answer. Yes. Rule 2, Section 4 provides that when two or more suits are instituted on the basis of the same cause of action, the filing of one, or a judgment upon the merits in any one, is available as a ground for dismissing the others. A judgment on part of one claim can bar a second suit over the rest.
What the law says
If two or more suits are instituted on the basis of the same cause of action, the filing of one or a judgment upon the merits in any one is available as a ground for the dismissal of the others
Rule 2, Section 4 — Splitting a single cause of action; effect of. Read the full provision →
What Rule 2, Section 4 provides
Rule 2, Section 4 addresses exactly this situation: "If two or more suits are instituted on the basis of the same cause of action, the filing of one or a judgment upon the merits in any one is available as a ground for the dismissal of the others." A judgment on the merits in one suit can be raised as a ground to dismiss another suit built on that same cause of action.
Why 'same cause of action' is the key phrase
The rule does not bar a second lawsuit simply because it involves the same parties, or arises from a related dispute — it turns specifically on whether both suits are "instituted on the basis of the same cause of action." A single cause of action generally has to be litigated as one whole, not split across separate suits filed one after another, and this section is what makes that principle enforceable against a second suit.
Why a partial judgment reaches the whole cause of action
A judgment on the merits, even if it only resolved part of your overall claim, is a judgment reached in a suit based on that cause of action. Because the rule ties the dismissal ground to the cause of action itself, not to how much of the claim any particular suit happened to cover, that judgment can be raised as a ground for dismissing a later suit that seeks the rest of what should have been litigated together in the first place.
What this depends on
Everything here rests on whether the second lawsuit is truly built on the same cause of action as the first, rather than on a genuinely separate and distinct one. The statute does not define what makes two claims the same cause of action, so that is the question that actually decides whether this rule reaches your situation — if the "rest" of your claim is legally a different cause of action from what the first case resolved, this particular ground for dismissal would not apply in the same way.