No, you do not need the 2nd FPERIOD().

FPERIOD() returns the number of the Fiscal Period that you have selected (i.e. 1 through 12).

Andrew uses the first FPERIOD() to create the parameter to the function ADGET(). For instance, in period 12 you need "P12". It varies depending on the Period you choose.

But in the 2nd ADGET(), you already know that you want "P 1". It will never change. Therefore FPERIOD() is not needed.