This was done on Dash 8 300's in case anyone was wondering.
Registered where?
UK CAA has a different FI gate requirement, separate for each PL i believe.
Rest of the world if one trigger is up they should both go thru as the gate cam/mechanism is a single piece..
I know if one PL is below FI the other will go straight thru as well - use it when I'm rigging power lever layshaft microswitches so you get smooth operation thru the gate especially setting up the beta backup switches which are at FI -2deg.