Using the Mac OS to move or copy is fine, no problems.
Using PhotoLibrary to move is ok too, just when using PL7 PhotoLibrary to copy that the double file problem manifest itself.
Unfortunately I don’t have a spare Windows PC around to help test things there.
OK - So, you can now report this finding to DxO Support: You have confirmed that PL is seeing your source AND destination folders as being one-and-the-same … it should not be doing so.
I found that a single move is no problem in DPL7’s PhotoLibrary. But: Moving files there and back again left the database with duplicate entries and files that did not exist or duplicate files where only one existed.
Try making a virtual copy of one of the duplicate files and see if you can replicate the strange problem where just going back and forth between different folders in the Photolibrary automatically created more virtual copies.
Certainly some fundamental issues with the Photolibrary but nothing too dramatic if careful.
I did lose some corrections but maybe that was just from making those corrections in PL7 and going back to PL6. Not confirmed though.
Confirmed. Changes from PL6 show in PL7 but not vice-versa.
Just incase you don’t want to have to re-edit, you can modify the version numbers near the end of the .dop files. DPL6 will then read the .dop files and simply ignore edits made with features that are only available in DPL7. I’ve done such mods occasionally with earlier versions of DPL on my Macs, but in general, it’s good practice to edit with exactly one version.
Same thing is possible with presets, but again, results depend on how big the differences between versions are.