Should I have a separate copy of all CakePHP files for every new application?

I'm extremely new to CakePHP. From what I've gathered, it seems like I can have multiple applications that all share the same app and cake directories.

So, let's say I have two applications. CakeFacebookApp and GenericCakeBlog. These applications are completely separate from each other and will have completely separate URLs, but they will reside on the same webhost. Should they both be within the same cake structure, or should they each have a full cake install in separate directories?

Technically, I'm sure it will work either way, but I guess I'm looking for a best practice approach. Thanks.