I have been training this barberry for years now and always I had thought that it was one plant with several trunks (that I reduced to just two). The dead part had started to rot out and get soft so when I repotted the plants I was able to see more clearly that they had been seperate plants all along. They came apart easily and with nice compact roots. Here is an image of one of the new plants and an image of what it looked like before, in case you don't remember.
