Do you mean that splines are imported from the library ?
This may be problematic, because currently RaillClone tries to reuse the splines assigned to the current object, which is the desired behaviour in many cases (for example you are testing different styles over a fence path). Also we should delete the existing splines before merging the new ones, but they could be used by other objects.
I'm afraid there are too many exceptions for making it work in a safe way.