Can Renata Hostile Takeover her own unit that was Hostile Taken Over?

Yes, you can use Hostile Takeover on a unit you have already taken control of with a previous Hostile Takeover, provided that unit is currently considered an "enemy unit" from the perspective of the second spell you are casting.

The Ruling

• Targeting: Hostile Takeover requires you to target an "enemy unit."
• Control Interaction: If an opponent uses a Hostile Takeover on your unit, they become the controller of that unit. From your perspective, that unit is now an "enemy unit," making it a legal target for you to play your own Hostile Takeover.
• Resolution: When your Hostile Takeover resolves, you gain control of that unit from your opponent and ready it.

Important Considerations

1. Duration Conflict: Both instances of Hostile Takeover have the duration "Lose control of that unit and recall it at end of turn." Because they are separate effects, both will attempt to resolve their duration-based instructions during the Ending Phase.
2. Recall Priority: If the unit is under your control when the turn ends, both effects will trigger their "lose control/recall" instructions. Since you are the current controller when the cleanup phase occurs, the unit will be recalled to its owner's base. (As established in RiftJudge FAQ #7666, the owner is the player whose deck the unit came from.)
3. No Chaining Conflicts: You are not restricted from targeting a unit simply because it is already under the effect of another control-changing spell. The second spell simply overrides the current controller state, and both control-duration effects will eventually expire at the end of the turn.

This interaction is consistent with the rules regarding control-changing effects and the definition of "enemy unit" as a target requirement.