What kind of backup/copy do you want to create of the images that you want to delete?
Your regular backup of your Aperture library (a Time Machine backup, or a copy of the Aperture library on an external drive) will include the trashed images in the Aperture Trash.
If you want to export the trashed images to a folder outside the library, you need to remove them from the trash temporarily to be able to export them, I'd suggest to do it this way:
- Create a new project (File > New > Project) and call it for example "MyTrash"
- Drag the images from the Trash to "MyTrash"
- Then select the "MyTrash" project in the Library Inspector and export it; I'd suggest to export it as a new Library (File > Export > Project as New Library); this way you will backup the edited versions together with the original master image files.
- Check if the exported library works. Then put the images in "MyTrash" back into the Aperture Trash and empty the aperture Trash.
Also, if I am deleting duplicate thumbnails, do I select delete version or delete master and all versions.
You need to delete masters and all versions, if you are doing this to save space in your library. But do this only for images that are really duplicates, imported twice into Aperture.