Front discs - 1 warped, 1 not. Looking for advice opinions, help, sarcasm etc.

[Fizzy Pies]

The run out tolerance on the front discs is 0.2mm.

The RH disc runs out 0.6mm.

The LH disc runs out 0.075mm.

First why would they be different?

Second is it worth replacing only the bad disc? If so would a used one be better?

Thanks