iPhoto keeps importing duplicates I have a "MyPictures" folder in which I keep my photos. I do not want iPhoto to manage my photos for me by copying them into its "Library", I just want to use the program "pointing" to the "MyPictures" folder. As I take photographs, I add them to the "MyPictures" folder; every now and then I'd like to update my iPhoto library "adding" the new photos just by "reimporting" the "MyPictures" folder. 

Whenever I do that, iPhoto re-imports the whole set of photographs, unable to detect obvious duplicates.

Could you kindly help me fix this, please?

My settings:


Operating system: Snow Leopard (10.6.8)  
Application version: iPhoto '11  
iPhoto library location: $USER/My/Application_Data/iPhoto, same problem when using defaults  
Home folder: uses FileVault, same problem when switching it off  


iPhoto preferences:


Importing (Copy items to iPhoto library): No, but also tried saying yes to that
Look up Places: Automatically, but tried many times to switch this off to no avail


Failed attempts:


Repairing library database
Rebuilding small thumbnails 
Rebuilding all thumbnails   
Recovering orphaned photos   
Repairing library permissions


I am at a loss as to what to try next.

It seems like iPhoto itself "adds some data" to the photographs so that it does not recognise the original as such anymore. Whatever the cause, it is very frustrating for the app not to know it has already "seen" that photo and to re-import it every time.
After waiting for quite a bit of time, I have to answer my own question and do so "negatively": doing what I want to do just seems impossible for the time being. Working with pictures one allows iPhoto to "duplicate on import" works fine, it just means that iPhoto will more than double the storage requirements for the photo library, essentially duplicating it and adding its own thumbnails, Places/Faces metadata, etc. How disappointing. :(