Here is a possible 'workaround' for the issue, but it
will take someone more knowledgeable about the Windows
Installer infrastructure to say if the workaround can be
applied directly as a clean solution or if it could have
hidden consequences.

Each 32-bit installation on 64-bit Windows has its own
'Uninstall' registry key under:

> HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall

named after its Windows Installer assigned GUID, e.g.:

> HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall\{A37F2D73-72D1-364D-BA5D-CEA430BCC040}

In that key there is a value named 'WindowsInstaller'
which for CPython installations has the value '1' (of
type REG_DWORD).

If you change that value to '0' (again, of type REG_DWORD),
the installation's 'Add/Remove Programs' dialog entry will
get displayed correctly, and user will be able to run the
installation (reinstall/change/uninstall) from there.