"He drank three bottles of Baijiu, and he is sleeping now."
Man, this one's a bit frustrating and is why it's so hard to "test out" and jump ahead. I had "他喝了三瓶白酒，现在在睡觉" but it rejected that and said it had to be "他喝了三瓶中国白酒，现在在睡觉" . I think the 中国 in that sentence is unnecessary and also would be much less common to use than what I had. Aiya!!
I agree with you, but is compassionate for Duo too because 白酒 is also commonly referring to 白葡萄酒 White Wine.
By the way if someone had drunk 3 of those he probably would not be sleeping but dead. Those are 60% proof or more.
现在 is a word by itself which means "now". The second 在 is to indicate that the action is continuous (is sleeping).
If Japanese helps, 现在睡觉 is いま寝ます while 现在在睡觉 is いま寝ています.