I have two machines each with the 8.5 toolset already installed.

downloaded the 8.6 CA Gen Workstation Developer Toolset WINDOWS-ALL from the Broadcom Product Downloads web page. On one machine I completed a silent install with ADDLOCAL=ALL and on the other machine I completed a Typical install with the Product Browser.

Both installs have the 8.5 and 8.6 Start Menu picks merged even though there's an 8.5 folder of picks: C:\ProgramData\Microsoft\Windows\Start Menu\Programs\CA\Gen 8.5
and an 8.6 folder of picks: C:\ProgramData\Microsoft\Windows\Start Menu\Programs\CA\Gen 8.6

What needs to be done so the Start Menu picks are isolated in their own folders?  i.e. a Gen85 folder and a Gen86 folder.  I can't tell what toolset is being launched until I do a Help > About

Release : 8.6

Component : CA Gen Workstation Toolset

Successfully replicated use case in our lab and Gen 8.6 and Gen 8.5 icons got mixed in Windows start menu CA folder. 

Apparently, any folders under the first folder in the Start menu do not appear but the files under them do. 

It looks as if Windows 10 is supporting single level of folder structure and in older Windows versions, it behaved differently.

Some  possible workarounds:

-You can't create sub-folders for the Start Menu-All Apps, but you can create links for them

Windows 10 Start menu not displaying the subfolders

-There is also the unlikely usable option to use a different Windows launcher to replace Windows start menu.

Start menu folders within folders