NOPE - can't be done. No copy feature. I been begging for one there for over a year.
BUT - in your case I got an idea.
If you have 100 or more items you can use the bulk lister. It's an excel spreadsheet. The image you upload has to be someone on the net - like stored here on Auctiva etc so it can be grabbed and put on ecrater. However, using the bulk lister you can only put one image per listing BUT you can then turn around and manually ad others if you need to.