Sounds like he's extra active and therefore extra hungry. If he's hitting all his milestones on time or near enough then I wouldn't be concerned but jusst to reassure yourself, a check up won't hurt.

I have the opposite; a boy who doesn't eat alot, loads of energy and growing like mushroom; sometimes it doesn't make sense but it's normal for them.

Haahaaa! Oh my, this brings back memories!  Three of my five were boys and I swear they come hollow!   I tried to get well balanced food into them every two hours, therefore they knew they were not going to be hungry!  With food not far away the urge to over eat was gone.   Sounds like your little guy is eating great stuff!  If his activity is up and you notice that he is not carrying extra weight and all else seems normal, well then get ready for when he is older!  As teens my guys and their friends tossed off regular full meals it seemed every two hours!  None ever got over weight.   I see this as quite normal, but then you are Mom, if you feel something is off than follow your instincts!