I am having trouble changing the plain zip file image to an image I want. I batch added the image with the same file name as my zip file and it changes the zip file picture, but I am getting a duplicate image in my gallery. Is there anyway to delete the duplicate image and keep the one for the zip file?
You're suppossed to upload the thumbnail file using FTP. You're not suppossed to add it to coppermine's database using the batch-add function. The idea is: coppermine will look up the folder where the zip file is stored. It will show the custom thumbnail if present and display the default one if not.
Re-read the corresponding section of the documentation (http://coppermine-gallery.net/demo/cpg14x/docs/index.htm#cust_thmb) and post deep links to the zip file and the custom thumbnail.