Don't fret about it. When learning new software, terminology is always a test. As every software has its own unique terms specific only to it. So don't get all upset. You are really doing well. And you ask super good questions that are helpful to others.
The message you are receiving "Duplicate Inventory record will become current record" simply means if you click Yes to duplicate, AW2000 will automatically move you to the new Inventory Item so you don't have to go looking for it. So if you duplicate Stock Inventory Item 1007 and your last record is 1200, Duplicating #1007 will mean you will now have 1201 and you will automatically be moved to 1201. I hope that makes sense.
Duplicate the Stock Inventory Item. Then make all the changes you need to make. Auction title, description, Reference ID, Category, whatever changes you need to make. Including being sure the images are correct. If an image isn't one you want to use, don't delete it, use the Exclude image option instead.
To exclude or reorder your images, on the menu, go to "Images | Order and Exclude Images' Click on the image you do not want to appear in this particular listing. You will see a box in the lower right hand side that says "Exclude this image from listing and websites" Click that box when the particular image is highlighted blue. And that image won't be uploaded when you list your goody.
Does that help?