Who got served first? The lead case will be the one in which parties were served first; not the one that was filed first. If two actions are pending in different courts of the same state, on proper motion, abatement in favor of the court whose jurisdiction was first perfected by service of process is mandatory. California Rule of Court 5.63.
Regardless of when each action was filed, the first person to get served is the case that controls. The first court to assume jurisdiction has exclusive and continuing jurisdiction over the subject matter, i.e. dissolution of marriage. If you were served with a petition for dissolution after you served your own petition, your remedies include a plea in abatement which can be made by a motion to quash service of the summons and petition.