yes seperate!!! we had that problem with two we bought from someone that said they did well together when we got them home we noticed one wouldnt leave the other alone in the end it became brutal before we were noticing the one was getting bit on its hind quarters she ended bloody it was so sad! we just totally kept them away from each other until one day my daughter was holding the nice one and the mean one was on the floor the kids were playing with them and the mean one walked over and totally knawed up my daughters arm within seconds she had 14 large teeth marks in her arm we no longer have mean bunny.