I have a situation that I need help from other GMs; I have a player who is playing a HRD, he is actually a copy of a Moff, getting ready to replace the Moff as an agent of a Hutt.

Here is the plot issue:

- They are going to be arrested as saboteur for the Alliance, then transfered to a prison. They will all be drugged (droids are going to be put a Restraining bolt), but what about that HRD? He looks human, he even looks like their boss, drugging him wouldn't really work (he's a droid afterall, but the Imps are going to think he's a look-alike to the Moff. - very good look-alike!

How can I make him unconscious for the travel, like his other partners, without giving too much into the fact that he is a HRD to the Imps?

Depends on how well they're disguised ideally if they're knocked out by whatever knocks out the droid would work as long as you use knock out gas on the others so the Imperials have no reason to take a closer look.

An ISB Agent might be interested if they notice the resemblance, but as long as they aren't held long enough for someone to run a medical check and they're not wounded enough to reveal their secret I guess that's up to you.

He's an HRD.... I'd make him do a deception check with a boost or two to "appear" drugged. If you wanted to go further, you might give him a discipline check to fake it for the entire trip (or expected duration). You could even give him a medicine check to determine what the appropriate effects are supposed to be and how long they're supposed to last so he can replicate it. It's a common trope that the hero is immune to whatever substance is used on him, but deceives the guards into thinking he's incapacitated in order to sneak into a facility.

Use an electrical based attack (cattle prods or ion blasters) to render the humans/droids temporarily unconscious.

If you choose to use drugs then place them in coffin sized storage tubes, the HRD May wake up but will be unable to do anything.

Shackles and a brig work just as well as drugs, if they can't escape or see anything does it really matter if they are unconscious during the trip?

Frozen in carbonite is a cliche but will work.

Restraining bolts IIRC require the bolt to be put near the Motivator to inhibit the droid. But RAW stun blasts should do the same. Even stasis or carbonite would work

If you have the background that he's designed for infiltration, you might have programming that will control his actions. For instance, if his "taste sensors" detect a sleep agent in his food, then his programming would automatically reproduce the effects of the drug on his system to ensure a detection proof reaction. As a safety measure, his "subconscious" programming would then keep track of his surroundings using his systems in a "sleep mode" to ensure the safety of his chassis. In the event a mission threatening situation came up, he would then "wake" to defend himself.

This basically means that he would act like everyone else until he was directly threatened, and thus be able to go along with plot machinations that you introduce.