Can an employee perform accounting clerk duties at one rate of pay for 15 hours per week and then perform payroll duties 1-2 days a month at a different rate?

Alternatively, can this employee (who has a bona fide accounting business on the side) be an employee for the payroll clerk function and an independent contractor for the payroll function? The employer currently hires an outside firm for payroll.

Thanks in advance for any help!

I guess if all parties involved agree to the pay rate for specific jobs then yes it can be done.

You can be a 1099 worker and also be an employee doing a different job.

And yes you could have two pay bases, but there needs to be an agreement about what happens in over time issues.