This question already has an answer here:
If George had stocked on some of his hairs before his ear got cut off by Snape, could he have used polyjuice potion to turn into a version of himself with both the ears?
From Goblet of Fire we know that polyjuice replicates deformities of the target, when Barty Crouch Jr Changes into Moody and has all his scars and fake leg.
We also know it replicates better body conditions from Chamber of Secrets, when Harry no longer needed his glasses after turning into Crabbe.
Would this be true if the body part had been cursed off by dark magic as well?
(In fact, in case of the twins George probably didn't even need to have a stock of his own hair, he could just polyjuice himself into Fred and no one would know the difference.)