This behavior is By-design and normal since you are running TS in APP Mode. The purpose of Install mode is to enable the TS to run application for Multiple users.
When registry entries are made to HKEY_CURRENT_USER\Software they are echoed to the
Shadow key area.
For any new user, registry entries are copied form the Shadow key to the User's
Profile in registry (HKEY_CURRENT_USER).
This is to make sure that an application installed on the Terminal Server can run
under any users profile.
==========================Description on the TSCUINSTALL value in RUNONCE
key=====================
Key:- Default user key HKEY_USERS\.DEFAULT\Software\Microsoft\Windows\RunOnce
Value Name:- tscuninstall
Value Type :- REG_EXPAND_SZ
Value Data:- %systemroot%\system32\tscupgrd.exe
This value is responsible for the following:-
(1) Deletes short-cuts on the desktop with the target "mstsc.exe".
(2) Deletes the "Terminal Services Client" and "Terminal Server Client" entries
from the Start Menu.
(3) Deletes the client files from Program Files.
(4) Removes registry key that do not contain user settings.
(5) Uninstalls the TSAC MSI files using MSI routines.
(6) Run mstsc.exe /migrate to migrate settings from the registry into RDP files.
Thus the purpose of having TSCUPGRD.EXE in Runonce is to migrate any old Terminal
Services client settings to the newer RDP Client and uninstall Terminal Services Client.
