If you open two copies of Laserfiche, you cannot copy from one to the other. I don't feel like this has always been the case. If you drag and drop it essentially does an export/import process.
This is inconvenient at best for some of our users, as they have a hotkey from another system that opens Laserfiche and does a search. When they do this, it's effectively isolated from other Laserfiche windows they have open.