First of all, chickens, even 2 week old babies, are pretty tough so unless they are behaving strangely besides the big crop, I suspect they are okay.
If you just noticed today, I would take a look in the morning and see how the crop looks. If the crop has shrunk during the night or it's not as hard then they are okay, just eating a lot which they do at that age. They are little eating machines! AND their digestive systems, including the crop, can be a little slow to get going efficiently so that you don't see such a large crop. That is okay and that's what the cornmeal is supposed to help.
I took their food away at night just to see if the crop issue would disappear and that helped too. Also, if you have a light on them all night and all day to keep them warm, that will cause them to get up in the middle of the night and eat. When I was able to move mine to a heat lamp that didn't produce light at night, they would just go to sleep until morning and that and the cornmeal seemed to solve my crop problems.
So those are a couple things to try. Also search this website on large crop or "bulge in neck" -- that helped me.
It's amazing how much food the little things can stuff into their crops without hurting themselves, so if you are sure that they havent' gotten into anything that's not food, again, I think they are probably okay. (One of my neighbor's chickens managed to eat a bunch of screws and got those in her crop, now THAT was a problem).
Hang in there. I was absolutely terrified the first time I saw one of mine with that big bulge from her neck to her shoulder, but she is fine to this day and her crop is not noticable anymore.