[plib]

The difference is that the original isn't deleted from my master library. If I notice I clicked the wrong line then I could fix it as you outline. If I don't notice then the original is gone from the master and if any point in the future I use the master to overwrite any of the subsidiary libraries, which I sometimes do with the network library, then the book is gone entirely.

I could live with a dupe in one of the subsidiary libraries a lot easier than I could with a deleted book from the master library. Plus, in the nature of things, it's easier to spot a dupe than a deletion.