This has been discussed... Sorry I don't have time to search out the section... But the GUID gets duplicated and then forever more you are screwed.
It is, in fact, worse than just seeing the DUPLICATES show in the library loading dialog. Sometimes, AC will REPLACE one of the duplicates with the other when you open a file!...
I had this happen a lot when building custom windows. Kept replacing my cool custom windows with an EMPTY opening that I also created.
bugger...
Duane
Visual Frontiers
AC25 :|: AC26 :|: AC27
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DellXPS 4.7ghz i7:|: 8gb GPU 1070ti / Alienware M18 Laptop