When we create a new world if you talk to a pnj he will sell you something.
If you recreate the same world with the same seed he will sell you something else.
This is again the persistent seed world i think?
Try this seed to recreate the problem : -1635332903
you spawn directly into a village. Talk to the forgeron each time you recreate the seed he will sel you something new.
Pretty pretty sure this is Works As Intended as villager trades are not bound to a seed, they generate randomly.