Are you sure it is moulted fur and that they haven't just had another fight while you were away? If it's moulted, assuming you have a lop that moults like my Sprocket, then the fur should be in little matts, some with a narrow point of hair. There should also be some loose underfur in his coat. If it's been pulled out the hairs tend to separate easily and look more like loose clumps. plus if it's a lot that has suddenly appeared on the floor them it might point more to fur that's been pulled out, whereas if it's been mainly where he's sat or laid down then that would point to moult. Just my experience.