It is always recalculating RIDs now and it should be overwriting them too I think (as I'm writing this I'm questioning myself, though -- I need to double check, but I think Central uploads always rewrite the comment field). The problem I was referring to was that I internally keep track of those RID's so I can quickly find matches and I believe I'm not updating that when you replace -- quitting and restarting jEmplode after replaces would fix that, but it should only be a problem in a very few border cases (RID collisions between the old tune and the newly replaced tune)