Is Vickers a robot - does it have a double meaning when she calls Weyland father?
Nope, Ridley's pretty pleased with the father / daughter dynamic, and the fact that she's essentially on the mission to impress her dad, and keeps coming back to the subject throughout the commentary.
He confirms that Vickers is definitely not a robot during the scene in which Janek asks her the question directly.
"This scene here is comical in one sense because he's saying to her 'Hey, are you a robot?' And at one stage I was thinking 'Well, do I need it?' But the scene is so good and so amusing that I thought, 'Why not?' But it also aligns with the scene in the blue corridor, where she asks David what the mystery person said.
"Now here Janek's saying - and he's being amusing - saying, 'You a robot?'
"But he kind of means it, because he knows David's a shipboard company robot, whatever you want to call it, I think a company employee would be the best description, is she another employee? So even Janek hasn't twigged who she is."
Who she is is Weyland's daughter. There's no deeper mystery than that. That's the film's Ash twist.
Later, Ridley says of David...
"They said, let's hide the fact he's a robot, and I said no. I've done replicants, there's been a trillion robots, let's just make him a company employee who happens to be a goddamn robot."