is it the same litterbox?

I see in your profile that they are not spayed/neutered? At 6 months hormones will have kicked in. The droppings around the second litter box could be territorial battles. If they are not fixed, they should be separated NOW as they are likely to fight! Unfortunately rabbits who have lived together as babies do not stay bonded once puberty hits. If one is male and the other is female your doe may already be pregnant and they also need to be separated to avoid oops litters! Once you have had them both fixed they can be slowly re-introduced and properly bonded. There are some great guide pages in the bonding section of the BB forum

ThorBunny made some excellent points already, so the only thing I can add is when my two were in a small space, the tended to use their litter box more consistently. Now they’re free range, they’re still pretty good, but they do tend to be lazier (it’s quite a big space they have, 20ft x10), and poop outside the box more, almost as if they can’t quite be bothered to make the journey to the tray if they’re comfortable bunny-loafing in one corner. How big is their litter box? When I switched to a bigger litter box for my two, that seemed to help as well.