I dont know how the integras stock radio was set up, but the one I had in a previous card had 2 plugs in the back of it.
The plug in your picture actually looks like the wires that are coming from the main plug, (the one furthest from the radio that is connected), are doubled up. If thats the case, the extra plug is unecessary. The orange wire is probably a remote wire for if you were to run an amplifier.
If the deck works with the plug already in it, then you dont need to worry about the other plug.