Years ago this warning may have had some validity, but it is no longer a concern. Multiple burning programs can be installed without problems.
What you shouldn't do is install more than one packet writing program at a time. Most packet writing programs are imbedded in the operating system at system start-up to allow drag & drop operation from Explorer. If you try to install extra (imbedded) packet writing programs at the same time their drivers will all be active and you will have problems and conflicts.
So, if you want to use packet writing, choose DirectCD or InCD, etc., but not both.