To start, based on age I assume your rabbits are not fixed yet (spayed/neutered). If you are keeping them together, please note that if they are male/female, the possibility of a litter is very high. In addition, regardless of sexes, the emergence of hormonal drives can cause young rabbits who used to get along completely fine to become tense and potentially dangerous. Young rabbits will get along very easily with other rabbits due to the absence of hormones, so often it catches owners off guard when two rabbits they have had for a while suddenly get into fights. It is natural, due to hormones, and the safest recommendation is to separate them until they are both spayed/neutered and then go through the bonding process (more info in the RABBIT INFO section of this website).
At this point, the recommended diet would be unlimited timothy hay and a limited amount of “boring”, uniform pellets. Veggie introduction could occur around this time as well. In reading your post, I found myself wondering if you may have instead been witnessing poops resulting from upset stomachs, rather than just cecotropes? Sometimes when rabbits get gassy due to hasty food introductions or getting exposed to food not yet compatible with their gut biome, it can result in less formed poop. That being said, having more cecotropes left behind is somewhat more common for younger rabbits because at the same time, they tend to be on diets really dense in nutrients, like alfalfa-based pellets (in bigger quantities as well) and alfalfa hay. I would recommend not worrying about veggies right now and focus on maximizing hay consumption and limited adult rabbit pellets (timothy-based).
Re: the hay-eating behavior, rabbits are naturally foragers, so it is absolutely normal for them to eat a pile hay with discernment — they eat the “best” strands first, and then will revisit for the 2nd best, 3rd best… etc…. as they get hungry. Ultimately, no rabbit eats all strands of hay. It is inherently a part of rabbit ownership that you throw away “good” hay, unfortunately. Ways to encourage more hay eating is ensuring there is plenty of hay and hay locations to engage the rabbit’s foraging instincts. In addition, limit the access/quantity of non-hay food items, so pellets, veggies, and treats. You can imagine with a human child, you set out a plate of vegetables for them all day– children will eat it if there’s nothing else, but if they are occasionally given slices of cake, some potato chips, etc… throughout the day, they will just continually ignore the vegetable plate. Rabbits can be the same way– if a rabbit learns that hay is only what they have access to for the large majority of the day, they tend to increase their hay appetite.
The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.