I can reproduce it using an older submitted version and the latest version. Quite simply, if I create a new project and import ONLY v 2.14j15a of my asset, then import 2.15a29a, it will create new files rather then overwrite. Hmm, while typing this, it made me think. As I recall, I created a new project at some point in the past for testing and simply copied the source files into it and I ended up using it as the main folder, that would explain the differing GUID's. Sigh, probably the case.