When you save a file from the document library, it gets saved as DLFE-# even though the display name is different.
Files require a primary key so that there is a way to distinguish between multiple documents that have the same name. (The primary key that is used is DLFE-#)
The problem that occurs is that when you upload a document to the portal and then save it to your computer, the file name gets changed to DLFE-#.
For example, if you upload a file called "New Text Document.txt" to the portal and then save it to yor computer, the file name will get saved as DLFE-1.txt