MarkB
Legend
I think the bigger question is what it would do to Durkula's control over Durkon's imprisoned spirit.
Depending upon your interpretation of the spell's effect and Durkon's current status, there's a chance that he might be in control of his own body so long as the amulet is active.
Protection From Evil said:Second, the barrier blocks any attempt to possess the warded creature (by a magic jar attack, for example) or to exercise mental control over the creature (including enchantment (charm) effects and enchantment (compulsion) effects that grant the caster ongoing control over the subject, such as dominate person). The protection does not prevent such effects from targeting the protected creature, but it suppresses the effect for the duration of the protection from evil effect. If the protection from evil effect ends before the effect granting mental control does, the would-be controller would then be able to mentally command the controlled creature. Likewise, the barrier keeps out a possessing life force but does not expel one if it is in place before the spell is cast. This second effect works regardless of alignment.
Depending upon your interpretation of the spell's effect and Durkon's current status, there's a chance that he might be in control of his own body so long as the amulet is active.