Wiki states:
Loses all copy images, and takes damage and/or becomes enfeebledThe caster is hit by an AoE magical WS such as Blood Saber, or an AoE spell such as Firaga.
The caster is hit by an AoE enfeebling spell like Breakga.
Note: Some spells (e.g. Diaga) and WS's (e.g. Negative Whirl) can strip copy images, damage, and enfeeble at the same time.
http://wiki.ffxiclopedia.org/wiki/Copy_Image
so not officially clear anywhere lol