Hey Fiona,
I think your girl may be having a growth spurt--especially if she has started drinking a second bottle at night within the last few months.
My son is 16-months-old and a friend came to visit us a couple of weeks ago and said, "Is it just my imagination or has your son been eating the entire time I've been here?" It wasn't his imagination!
Right around 12-14-months-old he went from eating very heartily to kind of being picky and pokey about what he wanted to eat--so we were really concerned about him because some days he really would only eat a few crumbs all day long!
Then about 2 months ago (15-months-old) he just started having this amazing appetite. He would eat a solid breakfast (if it were French toast for example, he would eat 2-full pieces by himself and maybe some extra fruit!), lunch (usually rice with meat and veggies--at least 1-2 cups!) and dinner (whatever mommy and daddy were eating--but again, just as much as at lunch!). And then he was having snacks in between--fruit or some type of grain snack and lots of water (we don't let him drink juice) to wash everything down. Clearly, he was eating and drinking enough during the day.
Then he would have a 10-ounce bottle of milk before sleep and wake up at 2-3 in the morning wanting another bottle. We tried what we had been doing previously--just let him go back to sleep on his own because in the past his waking was just habitual waking. But after 5-10 minutes it was clear by his cries that he was actually hungry--not wanting to play. He had a "desperately hungry" cry going on. So, we fed him another bottle and he sucked down another 10 ounces! And got up the next morning at 7-8 am ready for a big breakfast again.
Plus, our son has started sleeping a ton more than he did in the past. Sometimes he will take a 5-hour nap in the afternoon and be ready for bed at his usual bedtime, "begging" us to get him to sleep again.
So, clearly, he is growing a lot.
Before you weed out that other night feed, I would check and see if maybe your daughter is getting ready to have a huge growth spurt and if that might be the reason for her need for that extra bottle.