Can a 12 panel hair drug test differentiate between hydro codone and hydromorphone if hydrocodone is already depostited in hair ?

Yes, it can. Even a 10 panel can do that.

Can a 12 panel hair drug test differentiate between hydro codone and hydromorphone if hydrocodone is already depostited in hair ?
Yes.

Yes it most definitely can. Now days they are so effective that I think they can go back as far as 7 years depending on how you let your hair grow