Yes, it occurs most when we get a dwg/subd. from another engineer that doesn't have the same template as us. So, we get extra styles by default when we take any civil 3D objects from them. Not the best case to work with but happens a lot, and don't have time to redo from scratch. Carlson is somewhat common here so have seen that one too raise the hair on the back of my neck dealing with there junk.
MJP