Hi J.,
My twins are 18 months old and sometimes they sleep through the night, and at others they don't. It depends usually on their teething cycles, with each new teeth giving them problems and waking them up at night. They do not eat at night, they stopped at 12 months, naturally. And they like to fall asleep with their security toys. Maybe your boys have some toy which will comfort them?
You've got a lot of advice to "let them cry it out." I have to say that from my own intuition and psychology training I know that cry-it-out is not good for babies. It is very exhausting and tiring for a parent (and I know what it's like first hand), and I'm sure there are some methods to help babies fall asleep better, but letting them cry-it-out, is harmful, no matter what the "common wisdom" is saying. There is NO rule as to when kids have to start sleeping through the night. They need their comforts, whether that's a hug, a security toy, or a bottle as long as they need it. Maybe you can experiment with different ways of comforting them. What if you have them in arms, and then lay down next to them and gently stroke their backs? Also, having a bottle before falling asleep is absolutely normal for this age and up until much later. My boys do not drink at night, but they always fall asleep with a bottle. I do not think you formed any "bad habits" in your children by nourishing and comforting them, it only benefits them now and in the long run. Of course, it is tough on you, but hang on there, it will pass, and meanwhile you may find other methods in making them feel comforted and secure.