Knowledge of release khayeñāṇa, or Dukkha-nirodha-gāminiyā paṭipadāya ñāṇaṃ (Knowledge of the way leading to the cessation of suffering), is the effect of the path. Now knowing this, of cause needs to attain certain liberation vimutti at first place. Once attained this knowledge guiding to certain vimutti, can be reproduced.
There is no such as a contradiction, but is simply a change of perspective, one toward fruit, and one having left fruit behind.
Other then mentioned in other answers, release and knowledge of release are not only something that occurs only to an Arahat, but to certain extent for all other stages of awakening. In full extant and so also full repeat-able, of course only for an Arahat. Knowledge at the "end", with the breaking up of the body, will then be abounded and final ceto-vimutti, pañña-vimutti attained. Release is the only left then.
(Note that this is not given for trade, exchange, stacks and entertainment but as a means toward escape from this wheel here)