Does a company need to pay overtime to employees who work two different jobs, even if one of those jobs is a training position? This is in Washington State on an Indian Reservation. Example: Employee is a cashier making $9.00 per hour and works their 40 hours per week, then takes a blackjack training class for 20 hours at $5.15 per hour in the same work week?

That is not a simple question to answer. Some training time is compensible, some is not. Much depends on whether the training is voluntary and whether the employer "derives a benefit" from it. If you don't have legal counsel you can consult, then I suggest you contact your State's Department of Labor/wage and hour division and inquire.

P.S. If you do have to pay for this training time, then the employee will need to be paid time and a-half for all hours worked over 40 each week (including the training time), using a weighted average of the two pay rates. You'll want to discuss that with the DOL too, to make sure you get it right.

P.S. I am assuming you are the employer. If you are the employee in training, you can also call the DOL to determine if you must be compensated.

My question would be if the person is receiving two different paychecks, or one paycheck showing both jobs. I would say if there are two different payrolls that it is treated like a person having two jobs. If the jobs are on the same payroll, arguably, then it is two different positions with the same payroll employer. I suggest talking with the state department of labor, but if the jobs are different, in different locations, are two different types of work, two different supervisors, different payrolls, different job descriptions, different in time of when work is done, then I think you treat them as two different jobs and would not commingle overtime or pay or work rules, and treat each job separately for the purposes of imposing labor regulations.

but if the jobs are different, in different locations, are two different types of work, two different supervisors, different payrolls, different job descriptions, different in time of when work is done, then I think you treat them as two different jobs and would not commingle overtime or pay or work rules, and treat each job separately for the purposes of imposing labor regulations. elklaw, that would violate wage and hour laws. There just isn't any wiggle room on this. If the individual is doing two jobs for the same employer, overtime must be paid based on the total hours worked.
The only thing that's unique about this is that if the employee is receiving two different rates of pay, then OT is calculated based on a weighted average of the two.

Something you both missed is that this is taking place on an Indian Reservation. That means it is on what is considered a sovereign nation and Federal laws may not apply. The OP should check with a lawyer who is versed in the laws on the Reservation as they very well may be different.

However, had that not been the case, Beth is correct. It is the TOTAL hours for the employer that counts, not how many different jobs they worked. Back in the long-ago days when I administered payroll, I had some employees doing as many as four different jobs a week, but their OT was always, and must be, based on the total number of hours they worked. The different jobs only matter as regards the rate, since the OT rate is based on a weighted average.

So the weighted average would be $7.72?
40 hrs@$9.00=$360.00
20hrs@$5.15=$103
$360.00 + $103.00= $463.00
$463.00 divided by 60 hrs = $7.72