FD's off: they will pop up in TOGA. When you go out of TOGA in either roll or pitch that mode change will cause the respective FD bar to disappear. Thus if you select a roll mode HDG or LNAV the roll bar will disappear: if you select a pitch mode, or if it is activated automatically, e.g. ALT ACQ at MAA, then the pitch bar will disappear. Therefore each bar is independent. Recycling and displaying the green FD (with FD's out of sight) will ensure that after TOGA pop up they will remain in view and giving correct guidance when you move out of TOGA and into other modes.