Dealing with locked files
When idfilerep cannot replace a file because the file is locked by some process:
If there is no .busy extension version of that file, it leaves a copy with the .busy extension.
If the .busy version already exists, it leaves a copy with an .nnnn extension.
The timestamps on the files can usually be reliable enough to determine which file is newest by checking the creation time.
For an administrator to restore the correct version of the file, the newest file has to be renamed with the original file extension; for example, exe, dll extensions. The rest of the files should be removed to a backup location in case there was something important in any of them; they act as a tiny history for that file.