Are you sure that it’s not pee on the blanket? Rabbits do like to lick cloth, sometime to excess. I thought that my rabbit had peed on the sofa once, there was such a big wet spot, but then I saw that it came from her licking the cushion. Sometimes rabbits can drip water from their chins after drinking from a bowl. You also need to make sure that one or both of them isn’t drooling, which could indicate teeth problems.
You didn’t mention your rabbits’ genders and how old they are, and if they are spayed and/or neutered. If they are bunnies and you are not sure about their gender and they are 3 months old or more, they should be separated to prevent unwanted litters. Then after their surgeries, they can be re-bonded. Even if they are both the same gender, they should be spayed or neutered to prevent fighting and for health and behavioral reasons. Don’t just rely on what you were told. Many people have been told that they had the same sex rabbits, then they were later presented with a litter.