Can they get back to the litter box when they’re out hopping around? They should return to it if they need to go, but I suppose another litter box would be a good idea. Can you think of any reason Thumper would be pooping outside his cage? That’s a typical marking behavior, which you probably know. Maybe he’s wanting to mark the spots Remmy is marking.Are either of them neutered? Sorry. Maybe you’ve said this somewhere. Sounds like unneutered male marking, which would continue, but not sure where you’re at with them.

I would say yes to the second litter box where he is peeing the most, as they are routine pets. For pooping everywhere, it could be marking as megabunny said, but I’m unsure. Both my buns are fixed but they often times miss their boxes. I notice it most when they fall asleep somewhere. As soon as they get up, bam, its like the easter bunny got lost and dumped all his eggs at a single kids doorstep.

Moving to behavior.

Actually I just looked at her bio and I don’t think either of them is neutered. Erego… They need to be neutered and they should maybe even be separated until they are neutered because they will start to fight. The marking behavior is not likely to improve until they are neutered, so don’t knock yourself out trying to train an unneutered rabbit. You’ll be amazed at how quickly they will (most likely) get trained once they’ve had their surgeries. But they will still have the hormones for a month, so be wary of fighting in the meantime.