You can, and it won't hurt them. I doesn't really prevent cocci, but it reduces the chance that it will be that bad if they do get it. They can still develop the required immunity.
Dawg53 mentioned that there is no withdrawal. What he is talking about is that you don't have to wait for them to clear the stuff out of their system before you can eat the eggs. There is some differing opinion on that. My next comments are on the preventative dosage, not treatment level. Some manufacturers, Purina for one, state there is no withdrawal period for the eggs with the preventative medicated feed. Some authorities give a withdrawal up to 4 weeks. The government sites say there in no proof that you need a withdrawal period, but I've seen a few government sites that add that there is also no proof that you don't need a withdrawal period. Whatever all that means. I like what a bird vet said. He did not think it was a big risk because the Amprolium does not pass that readily through the intestinal walls. But due to the conflicting recommendations, he thought a one week withdrawal was reasonable. Being oversafe? Probably. All this discussion is about after they stop using the preventative dosage, not while they are on it.
I don't know what Purina or anyone else says about eating the eggs while they are actually on a preventative dosage. Personally I'd feel a little uncomfortable doing that, especially if I were selling the eggs to where a pregnant woman might be eating them, for example. I don't know that there is any danger or to whom. I just don't know that there is no risk. If you wish, you could check with the manufacurer to see what they say. Certainly don't take my word for anything. I'm not a medical professional.