ghost image

Etymology 1
From (noun sense 3, via noun sense 4).

Noun

 * 1)  Any undesired image appearing at the image plane of an optical system; either a false image of the desired object, or an out-of-focus image of a bright source of light in the field of the optical system.

Translations

 * Finnish: haamukuva
 * Hungarian:

Etymology 2
After the disk-cloning and backup software tool, itself an initialism of  -.

Noun

 * 1)  A copy of all the contents of a hard drive, used as a backup.