Or does it install alongside please? 
No, it is installed in addition to C8 and you can still use C8 or C8.5
New folder
Thank you…
Steinbergs site clearly states you have to uninstall Retrologue 1
and also you have to delete the old preferences folder.
Which means it installs right next to it but it affects it.
Where is this clearly stated? (I couldn’t find it)
Retrologue 2 installed just fine without uninstalling Retrologue 1. Also I did not delete my old preference folder.
Am I a rebel or what!?! 
It was in one of the PDF files…also, when purchasing Retrologue 1 then you have to
uninstall and i do not know if the same goes for when upgrading to 8.5.