Arrow Stock Apps related question

Hi all, I'm new to android, this is my first device.

I have noticed that some of the preinstalled apps - such as Layar and voice search - do appear in the android market but are marked as "uninstalled". Other apps on the other hand, such as google maps, appear normally as "installed" and can be updated as usual by visiting the downloads section in the market.

That said, my question is how do you update those apps that don't appear as "installed"?

Tried re-downloading layar from the market but it didn't replace the original layar app that came with the phone - it created a duplicate instead !