The game does count half golds generated by two dragons during intermediate times since I've collected from my 10 gold habitat early a few times and gotten 9 gold or 7 gold, so I see no reason why that shouldn't also apply to the 5 gold habitat and be able to collect 5 gold every 12 hours there. Eh, I'll find out if and when I save up enough gold to get goldwing, right now don't feel like messing up my collecting once every day routine using a 10 gold habitat and two 5 gold ones for four epic treasure dragons.