Dynamic Regular Date Earned Formula Required

Summary:

Need a formula to get the last two regular dates earned to update each month.

Content (required):

I have a Payroll Net Pay Variance report which compares the Net Pay against the last two Period Names.

Whilst we can't apply a dynamic formula to pick up the last two periods using the Period Name field, we can use the Regular Date Earned field to apply a formula to bring these periods back.

Is there a formula which can bring back the last two pay periods as in my screen shot below?

Its currently presented in a Pivot Table and I need it to show Balance Value and Variance between Period 1 and 2 only so excluding the 1 2023 Calendar Month, 30/04/2023 Variance column which is showing Period 12 and Period 1 variance.