This is definitely true, unless one uses the particular switches required to run multiple versions from one directory. I've never done it myself.
DSD+ 2.176
In -r1 mode, multiple copies of DSD+ and FMPx can run in the same folder and share the
DSD+ data files. Each DSD+/FMPx pair can monitor different sites or systems.
Use the -F<num> file name modifier on the DSD+ command line for each additional copy of
DSD+ to avoid file naming conflicts.
I have been running up to four instances in the same folder for years and have never had an issue. Each instance is named differently with the -F parameter.