What are you using for the details? I know in the database it flags a cloned module as xx__name - it uses 2 underscores instead of 1. Not sure if that will do anything or now. I will try to test it out now.
I'm out of the office ITIL training at the moment but I'll check what I did next week, I have a vague recollection of adding underscores but can't remember if it was 1 or 2!!