Short answer. Yes. The certification you signed includes a continuing undertaking: if you later learn that the same or a similar action has been filed or is pending, you must report that fact within five calendar days to the court where your pleading was filed.
What the law says
he [or she] shall report that fact within five calendar days therefrom to the court wherein his [ or her] aforesaid complaint or initiatory pleading has been filed
Rule 7, Section 5 — Certification against forum shopping. Read the full provision →
The undertaking does not end when you file
People read the certification against forum shopping as a snapshot — a statement about the world on the day of filing. It is not. Its third limb is forward-looking: if you should thereafter learn that the same or similar action or claim has been filed or is pending, you shall report that fact within five calendar days to the court where your complaint or initiatory pleading was filed. The clock runs from when you learn of it, not from when the other case was filed.
Calendar days, and where the report goes
Two details are easy to get wrong. The period is expressed in calendar days, so weekends and holidays are counted in. And the report goes to the court in which your own initiatory pleading was filed — that is the court whose certification you signed. Reporting it only in the other case, or mentioning it in passing at a hearing, does not discharge the undertaking the rule imposes on you.
Why prompt reporting is the safer course
The rule treats non-compliance with any of the undertakings in the certification as constituting indirect contempt of court, without prejudice to the corresponding administrative and criminal actions. Reporting late, or not at all, converts a problem about overlapping cases — which courts deal with routinely — into a problem about your own candour, which they deal with far less kindly. Disclosure is nearly always cheaper than the alternative.
Disclosure is not an admission of forum shopping
Telling the court that a similar case exists does not concede that you did anything wrong. The rule contemplates that a party may honestly not know, which is why the undertaking is framed around what you thereafter learn. What draws the harshest treatment is the opposite behaviour: where the acts of a party or counsel clearly constitute willful and deliberate forum shopping, that is ground for summary dismissal with prejudice and constitutes direct contempt.
What the report should contain, and what it does not decide
The certification itself indicates the substance expected where another action is pending: a complete statement of its present status. A report that discloses the existence of the other case without saying where it stands leaves the court unable to act on it. What the report does not do is resolve anything — whether the two cases genuinely involve the same issues, and what should happen to them, are questions for the court. Your obligation is disclosure within the period, not adjudication of the overlap.