I don't believe rares spawn with specific stats. You could have two 'viper tonic' (I know.. retarded example) ammys, but they may have entirely different stats.
is it possible to imbue some chain boots into impshanks? if so could u also use the roll back method to keep trying till you get them?
Yes, but the Imp Shanks will have different stats than the commonly duped ones. The mods that are on the duped Imp Shanks are not all possible to have spawn on boots anymore...
Rare names are not tied to their stats. I crafted a 'Corruption Heart' amulet that had nothing in common with the duped one.