It feels wrong, but with the Errata on Jack Daw's 'The Oldest of Magics' saying "This Ability cannot be negated or removed by any means," if you were to Mimic 'The Oldest of Magics' with the Doppelganger, wouldn't she keep the ability for the remainder of the game?
Someone please explain why it does or doesn't work this way, because right now I'm looking at it as Mimic grants the ability and at the end closing Mimic takes it away, but the ability granted says it cant be removed.