It's taken me a little while to figure out how to organize my library and now that I've figured it out, I'm cleaning up the database and trying to make sure that the photos I want in a yearly project are all there (i.e., all pictures from 2011 in one project). What I've noticed is that even though I thought that pictures were only able to be in one project in Aperture, I have the same images in two projects. My question is, which one is the Master (I've tried the referencing feature and it often tells me there is no reference) so I can delete the same images in a different project. Or can you tell me how to figure out if I indeed have duplicates in the library and that is why the same images is in one or more projects?
I checked the versions (there are three) and all parameters are exactly the same and the image number is exactly the same. Does this mean I have three originals?
If they are in three different projects you have indeed three different originals.
When you delete two of them and empty Aperture's Trash, you should find two different original files in the Trash bin in the Dock.