How to choose which Aperture duplicate photo to keep

Question

I use Aperture 3.4.5 on an iMac with OS 10.8.4 and, like many others who have written to this community, I have acquired lots of duplicates because some years ago I  moved from iPhoto to Aperture. Those collections are mostly referenced in their original collections. I quite understand how these duplicates came to be.  Using Duplicate Annihilator - Aperture  I have found a great many (4 thousand) pairs of duplicate pictures out of a library of 60 thousand, and as  has been explained by several responders, usually one is called iPhoto Original and the other iPhoto Externally Edited or iPhoto Edited.  I have never knowingly used an external editor, but I do understand that, in iPhoto, just rotating the photo from portrait to landscape will create a copy, something that does not happen with Aperture.  So that is why the dupliocates exist. My question is basically, now that I have found them, how to choose which one of the two versions to keep, because there seems no reason to keep these duplicates.
Obviously if I have made noticeable changes, or added many key words,  then I want to keep that one. The duplicates in question are in  two-photo Stacks. The original will have  a size of 3 MB or 4Mb and the copy will have a smaller size, maybe  as little as 1.5 or 2 MB.  Sometimes the copy has just been rotated (and the file size is made smaller). With Aperture I can rotate the original iPhoto picture and maintain the larger size. Sometimes (but not always) there is a name change from xxxx to xxxx.jpg.  But even without a name change, the edited or rotated file is smaller.  I have examined the two images at high resolution, in Aperture, and I cannot see any difference, though they have very different sizes.  This surprised me; there seems no benefit from the larger size, though there is a slight shift of the histogram of colors. (I do not plan to print any of these at high resolution, just show them on the iMac or a video.)
So my question is: is it desirable to keep the larger original file, though I do not see a difference in the image on my 27in iMac? I have many of these duplicates to choose between, and I would like to understand the consequences of my choice before I delete things. 

Answer 1

I would keep the larger as long as storage space wasn't an issue and if it was I'd look at increasing storage before deleting the larger file.
Think of it this way the larger files contains more data, more data means not only a better image (even if you cannot see a difference on the monitor) but also more options when you go to edit the image.
Cropping is just one obvious example.  A larger file will give you more options when it comes to cropping the image. 
You can always create the smaller from the larger, you can;t go the other way. Once you delete the larger file the data is lost for good.