Hi ConjurerDragon,
you only need to import the prof files.
The conf files are DOSBox configuration files, the prof files are D-Fend / D-Fend Reloaded setup files. Everytime you close the D-Fend profile editor it builds a conf file from the just edited prof file. In the DOSBox configuration file there is no section for defining mounts so they are written to the autoexec section. This means if you import a conf file D-Fend Reloaded will not show any drive in the mounting section of the profile editor but will show mount / imgmount commands in the autoexec section. So you can import conf files to D-Fend Reloaded if you want, but it's better to import the prof files. And importing both will make double entries.
By the way, there is a simple way to import many profiles at once: Close D-Fend Reloaded, open the "confs" subdirectory of the D-Fend Reloaded data folder in the explorer (normally C:\Users\<you>\D-Fend Reloaded\Confs"), open the D-Fend "confs" folder, select all prof files and, yes, just copy them to the D-Fend Reloaded "Confs" folder. That's it. The file format for the prof files in D-Fend and D-Fend Reloaded is the same (ok, DFR adds some more fields, but the import D-Fend -> DFR is just copying the files).