What I meant:
If they waste crumbles but not pellets, then they "need" more crumbles because they are wasting it.
If adding water means they cannot waste the crumbles, but they still go through more crumbles than pellets, then yes they are eating more. Maybe it's because of what the other poster suggested, that they eat extra when they first have access to a new feed they like, but then settle down to a lower level once they are used to having that feed available.
Can you post a picture of the label for each bag? (Guaranteed Analysis and ingredients.) Maybe there's some other nutritional difference that someone can spot, that would explain what is going on.
Of course it could just be that chickens sometimes do weird things