Have two machines each with the Gen 8.5 toolset already installed.
Downloaded and installed Gen 8.6 i.e. did a a silent install with ADDLOCAL=ALL on one machine and a Typical install on another.
Both installs have the Gen 8.5 and 8.6 programs listed under the same "CA" level in the Start Menu so it is not easy to distinguish which version is which.
There are separate folder created:
C:\ProgramData\Microsoft\Windows\Start Menu\Programs\CA\Gen 8.5
C:\ProgramData\Microsoft\Windows\Start Menu\Programs\CA\Gen 8.6
What needs to be done so the Start Menu programs are isolated in their own folders i.e. a Gen 8.5 folder and a Gen 8.6 folder.
It is not possible tell what toolset is being launched without doing right mouse button and use "More > Open file location" or after starting the Toolset use "Help > About".
Release : 8.5, 8.6
Gen Workstation Toolset
Gen Support see the same behaviour.
Apparently, any folders under the first folder in the Start menu do not appear but the files under them do.
The Windows 10 Start > Menu is supporting just a single level of folder structure and in older Windows versions, it behaved differently.
Some possible workarounds: