MediaMonkey forum

You could also try Track Redirection & Synchronization add-on if you want to copy tags from the one set of tracks to the another one:
1. choose Tools \ Track Redirection \ Create Redirections/Copy Metadata... option;
2. select Folders radio button;
3. specify Master folder (with old files);
4. specify Copy folder (with new files);
5. select tracks which you want to syncronize (if you click on the left topmost check box you would get selected all contained tracks);
6. click on the Synchronize button.

The requirements are that both sets of tracks (old and new) should be previously entered into the Library (e.g. using Add/Rescan Tracks to the Library option) and both sets of tracks should have exactly same file names, e.g. "03 - blah blah.flac" and "03 - blah blah.mp3".

You could synchronize more than one album at once as long as you have same folder structure with old and new files, e.g. for old files:
c:\My Music\Lossless\Rock\Pink Floyd\The Dark Side of the Moon\xxx.flac
c:\My Music\Lossless\Rock\Pink Floyd\Wish You Were Here\xxx.flac

and new files:
d:\My Music\Compressed\Rock\Pink Floyd\The Dark Side of the Moon\xxx.mp3
d:\My Music\Compressed\Rock\Pink Floyd\Wish You Were Here\xxx.mp3

you should specify:
Old folder: c:\My Music\Lossless\
New folder: d:\My Music\Compressed\

You could select which tags you want to copy to new files (Title, Artist, ...) in the Tools \ Options dialog box on the Track Redirection tab.