[Presale question] Duplicate of files in hard disk

I have just started using DEVONthink Personal edition and it seems like something I have longed for, and I’m already considering switching to Pro. However, before I go about doing that, I just like to know the following:

Whenever I move a file (say a PDF, a DOC, etc) to a Group, I realized it was actually being copied over and stored in DT’s own folder, while a copy of the same file is still sitting in the original folder, e.g. Download. In the long run, I would end up have duplicates of all files?

I can live with removing the files from original folders, but I just thought, could there be a way to move files over directly which makes life slightly easier? Or I’m missing something?

The next beta of DEVONthink Pro’s Sorter will support moving files.