Q: If employee works 3 hours, then takes a lunch break, then works another 6 hours, are they entitled to a 2nd lunch break?

A: The answer is no. According to the Division of Labor Standards Enforcement,

In California, an employer may not employ an employee for a work period of more than five hours per day without providing the employee with a meal period of not less than thirty minutes, except that if the total work period per day of the employee is no more than six hours, the meal period may be waived by mutual consent of both the employer and employee. A second meal period of not less than thirty minutes is required if an employee works more than ten hours per day, except that if the total hours worked is no more than 12 hours, the second meal period may be waived by mutual consent of the employer and employee only if the first meal period was not waived. Labor Code Section 512. There is an exception for employees in the motion picture industry, however, as they may work no longer than six hours without a meal period of not less than 30 minutes, nor more than one hour. And a subsequent meal period must be called not later than six hours after the termination of the preceding meal period. IWC Order 12-2001, Section 11(A)

https://www.dir.ca.gov/dlse/faq_mealperiods.htm

A: No. An employee is entitled to a meal period when he or she works 6 or more hours in a shift. Another meal period is not required unless the employee works a full 10 hours or more in the same shift.

Good luck to you.