I'm not quite sure why you would think that Photoshop Elements would duplicate your existing photos. If you have had Elements 9 installed previously, and have a catalog, the new installation will utilize that catalog. However, Elements isn't going to automatically duplicate all of your images. Images are never actually "in" Elements. Elements simply points to the images wherever they are located on your system.
Hi Jim, Thank you so much for your input. I have not installed Elements 9 as yet on the iMac. I am using iPhoto at the moment. This is a little light in the editing options and Element 9 (which I purchased at the same time as the iMac but was persuaded to try the iPhoto instead). I have a 1TB HD in the Mac with 158gb of spare capacity. Hence not sure how to or if I should proceed. Regards