I just got a reply to a rules question:

In response to your rules question:

When Manaroo passes a blue Target Lock token to a ship that already has one, does the receiving ship get to choose which one to keep, or does it have to discard the one it already had, per the rules for acquiring a target lock when you already have one?

If a ship with a target lock is assigned a blue target lock from Manaroo, the previous target lock is discarded.

Not the way I thought it was going to go, but I'm happy to comply.