[inopinatus]

How about ... a duress code that diverts to a system that looks like the real one but actually contains disinformation (possibly including a misdirection that makes them think you were on their side all along, so that they let you go)

[vidarh]

I'd say that in most cases, the safest approach to a duress code would simply be to give real access to the system, possibly with lower privileges if it can be done without too much suspicion, while also triggering an alarm.

The cost of maintaining a sufficiently real-looking system is likely to be very high, with the very real risk that it won't fool an attacker.