The source diskette was part of a household collection and may contain e.g. high score files that were not present on the original pristine filesystem. Check timestamps: any file dated 1990-01-01 or later, that isn't mentioned in help.doc, is likely not original.
The file dosbox.conf in the zip file is not original. Its purpose is to slow down emulation.
MicroCom Systems Reference Collection (c) 1989, all rights reserved.