I was recently asked by a friend of mine about an issue she was having in Lightroom 3 with her workflow. She had made the decision to convert her images to DNG files on import and wanted to use the feature in Lightroom’s import dialog box to make a backup copy of the original file at the same time to a different location. She also was using the rename file feature to make her photo file names more user friendly.
Her issue came about when she noticed that the renaming of the files worked just fine on the DNG files, but was ignored on the backup copy of the original file. The original file kept its original name. This resulted with her not being able to easily match up the original RAW file to DNG file if needed. I am sure that there were some reason for this, but if it was me listening to them all I would hear is blah blah blah. I can’t think of any reason good reason why the file name would need to stay intact to preserve the integrity of the non-converted RAW file.
In Lightroom 3, the workaround is to copy the images into the catalog with the backup and rename options selected. Then after the import is completed, you can convert the imported files to DNG. This will leave you with a DNG file and the backup original file with the same file name.
The good news is that this was fixed in Lightroom 4 and so if you want to import and convert to DNG, backup the original file and have the renaming apply to both files you can make it happen in the import process.