MC can save tags in a XML file next to each imported file. It's called a "sidecar". To enable it:
- Settings -> General -> Import & Tagging -> Sidecar Tagging Mode: Save in both Sidecar and internal tags
Then right-click on the files and do a Library Tools -> "Update Tags (From Library)", and check if new files called "original_filename_sidecar.xml" are created next to your DFF files.
On a new MC install, when you import the files these Sidecars will be imported too. If not, you can do a "Update Library (From Tags").
Caveat 1: not all fields are saved to Sidecars by default. You can open one of the XMLs in Notepad to check what it contains... if it's missing something you need, you have to go to Settings->Library->Manage Library Fields, and enable the "Save in File Tags" option for each field you need.
Caveat 2: Looks like MC only saves Sidecars for Audio or Video files. You may need to change the "Media Type" on your files to "Video" to have MC create the sidecars.