Software Deployment

I was under the impression that the Silverlight installation upgrades a previous version, meaning it takes the older version off?

Having 5.1.41105 installed, and files in

C:\Program Files (x86)\Microsoft Silverlight\5.1.41105.0
C:\Program Files\Microsoft Silverlight\5.1.41105.0

Installing 5.1.50907 over this,the Programs and Features entry changes, but now I have the following folders containing files:

C:\Program Files (x86)\Microsoft Silverlight\5.1.50907.0
C:\Program Files (x86)\Microsoft Silverlight\5.1.41105.0

C:\Program Files\Microsoft Silverlight\5.1.41105.0
C:\Program Files\Microsoft Silverlight\5.1.50907.0

Rule of thumb, uninstall the previous version first to remove 41105 and then apply the newer Silverlight.

Which leads me to ask, does this invalidate:

"

silverlight.exe /q

(doing a silent install from the .exe will also upgrade previous versions without the prior need to uninstall)

"

as per the Silverlight 5 deployment tips?

http://www.itninja.com/software/microsoft/silverlight/5-2022

Within an estate with a few thousand machines I imagine the older deployments have left a number of Silverlight folders behind. 

Am I free to manually remove these folders/files post install of a newer version or are they still required?