Thank you for this answer.

Wass looking for the same thing.

Hi, can you attach link to the Fiio device profile? I can't seem to find it.
I guess you mean *.mmdc file to import?

And are you sure that you don't have the files duplicated also in your library? The numbered suffixes are mostly added when two library files points to the same location on the device (based on masks in the Options > File Locations tab of the device profile)

First off, I am fully aware that what I am about to write might be inadequate.

I am using Fiio X1 II as my playing device and there is an unofficial device profile for it.
Today, when I was trying to sync, MM pointed out there is not enough space on my memory card (my library is ~100GB, my sdcard 128).
I was surprised since I had only added a few files to the library. After clicking OK, MM started syncing, but I noticed it was songs that were already on the device. I ejected the device and looked through folders and saw that there were duplicate files (all ending with "_2") of files that were there already. I didn't install or deinstall any files recently. I started to look and saw that there was a similar problem on an official profile:
http://forum.mediamonkey.com/viewtopic.php?t=90978

Is this a general error that may occur or my device profile specific? If general, then what is there to do? If device profile specific, will there be official profiles for Fiio devices?