Is it possible, installing a new Version of WD without overwriting the older one, so that there is the opportunity going back to the older one in worste case?
How does that work?
yes
this has been mentioned many times on the forum
simply install to a new location
then save a file there called 2wd
with notepad.exe
easy
you can then use that version as a test version (i.e say run in stationless mode)