best way to view it
from the data sheet

bit 1-0 SCS<1:0>: System Clock Select bits
1x = Internal oscillator block
01 = Timer1 oscillator
00 = Clock determined by FOSC<2:0> in Configuration Word 1.
when FOSC<2:0> = 100 is equivalent to 1x = Internal oscillator block ie they both set the same option (logical or )

but watch out if you want the pll engaged