No.  Your earlier versions of GPO stay unless you intentionally remove them at the library level.

If you have not already updated to the latest version of the ARIA Player it will update this to a new version with a nice new collapsing Library tree, but all of your Garritan (and any other ARIA Libraries you might have) stay intact and keep working as usual.

After installing things it's a good idea to check in the Info tab of ARIA and click all of the update tabs to get the engine and all up to date.

How do I locate instructions for the use of the garritan personal orchestra?  Matteo

https://www.garritan.com/user-manuals/ 

The installation fails because the following file cannot be located: 

12 Nasat f5.data

I get this message:  "An unexpected error is keeping you from copying the file. If you continue to receive this error, you can use the error code to search for help with this problem.

Error 0x80004005: Unspecified error